REVIEW: Topping D90SE DAC - Part III: Subjective Impressions, AMPT, and Summary. A few words about "warmth" and "accuracy" in sound systems.

This is the final part of my trilogy review/evaluation of the Topping D90SE DAC (see Part I, and Part II for the objective testing results).

As we end off, let's close with a discussion of subjective impressions developed over many evenings of listening (about a month or so). I've described the soundroom previously in some detail and for the two channel system, the main amplifier is my home-assembled Hypex nCore NC252MP, main front speakers are the Paradigm Reference Signature S8 v3, and dual subs (main Paradigm SUB1 with the little Polk PSW111). The Topping D90SE feeds my Emotiva XSP-1 preamp. All cabling is balanced XLR from DAC to amplifier (no need to fret, inexpensive Monoprice Stage Right XLR runs are all ya need, feel free to spend more on cables if you see fit of course).

I listened both with and without DSP room correction activated; generally I prefer with DSP. Knowing the frequency response characteristics (flat to 20kHz) and setting to "Fast Roll-off Linear" (Filter 5) allows me to use the same DSP settings for my room interchangeably with the RME ADI-2 Pro FS Black Edition without need to remeasure (equivalent frequency and time-domain performance). As discussed before, one of the benefits of a high quality DAC is that we can have even more headrooom with DSP processing whether it be full room correction or applying volume normalization like ReplayGain.

MEASUREMENTS / REVIEW: Topping D90SE DAC - Part II: Resolution

In this Part II of the review of the Topping D90SE DAC, let's focus on the performance that this DAC can achieve. As you can see in the picture above, I've got the machine on the test bench ready to capture some data. Given the anticipated performance as described in Part I last time, the E1DA Cosmos ADC is used for the measurements being presented today.

As you can see on the LCD screen, it's playing DSD512 (22.6MHz) material at the time of this picture. For a more complete examination of the device's performance, let's see if we can capture both PCM and DSD performance.

This device does have a broad number of features, so let's try to hit the key (and also some not-so-key) features to better understand how well it works and if there are nuances that the audiophile should be aware of. As readers here I'm sure are aware of over the years, objective testing can often show anomalies that listening tests easily miss due to the limitations of human hearing and cognitive ability. Sure, one could argue that inaudible limitations are not important. I'd like to think that in principle, audiophiles have an interest in achieving both technical perfection as well as immaculate subjective performance. 

MEASUREMENTS: DSD Testing with SoX-DSD Signals Part II (RME ADI-2 Pro FS R Black Edition, DSD Direct, Filter @ 50/150kHz) [Updated with 44.1kHz PCM --> DSD.]

 

Okay guys and gals, a rare "mid-week" update on DSD testing, a "Part II" follow-up to the previous article.

As I mentioned as an update in that article, I have a suspicion that the Topping DX3 Pro might not be using "DSD Direct" in its playback. However, I do have the RME ADI-2 Pro FS R Black Edition here as well. As you might know, I've been using the RME line of ADC/DACs for awhile now. These are certainly some very well thought out and high performance units with a ton of customization options.

Two of these options are shown in the screen in the picture above - "DSD Direct" and "DSD Filter". The "DSD Direct" is either OFF/ON, and "DSD Filter" either 50kHz/150kHz and is only activated when "DSD Direct" is ON, in recognition of course that DSD noise shaping does create significant ultrasonic content that in general probably should be filtered out; how much filtering is up to you.

MEASUREMENTS: A look at DSD and using SoX-DSD as a standard for test signal conversion. The 1/10-decade Multitone 32 test. And retro-pop remixes... ;-)

Hey everyone, although I'm in the middle of the Topping D90SE review series, I thought this week I'd make a slight detour! Like I suggested last week, I'm planning to savor the D90SE measurements / discussion series and enjoy the DAC. No rush needed. I see this blog as more educational and philosophical than mere opinions about things you can just buy and try for yourself. ;-)

Over the years, the fun part of the hobby and blogging for me has been to "evolve". As an audiophile, it's fun taking on the challenge of examining this pursuit with a more objective lens. To do that, it has been good to see what others are up to and incorporate incremental improvements in the testing gear and techniques I use within the budget of a home audiophile.

Each of these "MEASUREMENTS" posts is like a mini-experiment that we as hobbyist/"citizen scientists" can do for ourselves. I trust that the information I post can be repeated and verified if you have the interest, time, and some know-how.

Inspired by discussions with Bennet Ng (aka Dtmer Hk recently and in the Topping D10B review), DSD measurements is something that I have seen little discussions of in reviews. For reference, in these blog pages, we have talked generally about DSD/SACD back in 2013, looked at conversion software (here, here), as well as talked about PCM --> DSD playback like with HQPlayer a couple years ago.

But I haven't really taken a more intentional look at my DSD testing regimen... Something I hope to rectify here and clarify the "standard" signals I'll use in the tests ahead.

MEASUREMENTS / REVIEW: Topping D90SE DAC - Part I: The Hardware, Filters, MQA, and Jitter Performance

Today, let's start with what I'm aiming to be a 3-part review/discussion of the Topping D90SE DAC. I figure I'll take my time on this since things are busy around here and I hope not to purchase more hi-fi DACs going forward, so I might as well savor the moment. ;-) As a "more objective" audiophile who has a vision of aiming for "high fidelity" / "transparency", there is a clear target and end-point to what's needed from hardware performance especially with DACs.

Readers of this blog know that I've had a number of Topping devices reviewed here over the years. In fact, for any single brand of DACs, I think I've reviewed more Topping gear here than other brands. This, I believe, is a reflection of a brand that provides multiple products at price points with features that actually speak to me as a consumer interested in value which includes features, and price. I have certainly not been disappointed by overall quality to this point.

At a current retail price of around US$900, this is not an inexpensive model. As per most of my reviews, I bought this through usual retail channels so what I'm reporting on here is not any potentially specially-selected unit sent from the manufacturer.

Feature-wise, this is a DAC only but accepts multiple inputs - USB, HDMI-style I2S, S/PDIF Coax, S/PDIF TosLink, and wireless Bluetooth 5.0 (SBC, AAC, aptX [LL,HD], LDAC). While it has both unbalanced RCA and balanced XLR outputs, there is no headphone amp. For that, Topping recommends grabbing their top model the Topping A90 (~US$500).

What makes this DAC interesting in mid/late 2021 is that this is reputed to be the highest fidelity converter in the world (available to consumers) at this point in history, Topping's "flagship" device. 

Let's take a look...

MEASUREMENTS: USB Isolation with Nobsound ADuM4160 device and hi-res DAC. The world these days, and the audiophile microcosm.

 

After writing about very high resolution measurements with the E1DA Cosmos ADC last week and touching on basically "state of the art" fidelity like the Topping D90SE, for this week's post, I thought it would be good to talk about something more "fundamental". Often spoken of among audiophile tweakers but rarely have I seen evidence of actual value/effect for many of these devices.

Before I begin with this post or even show you anything, let me just say that I do not believe audiophiles need USB isolation for use with devices like DACs unless you know you have noise issues. I think we've all see indiscriminate suggestions that audiophiles need all kinds of noise filters and isolators (like this, or this). Sometimes these things cost quite a significant chunk of change compared to the downstream device (like DAC) itself!

Over the years, I have tried out a number of USB DACs with computers and simple streamer devices like the Raspberry Pi. With a normal set-up, I cannot say I have ever heard an issue with any of the various decent DACs I've tried. Likewise, measurements already suggest that in general there are no major noise issues with at least reasonable modern devices.

However, there are times when the system is complex enough where indeed you do see ground loops and noise like the 8kHz USB PHY noise pop through. A couple months back, I showed you some of this when we took the rather useless AudioQuest JitterBug FMJ for a spin in some of these situations! Today, let's look at the effect of that little inexpensive Nobsound ADuM4160 USB Isolator (typically can be purchased for <US$25) you see in the picture above.

EARLY LOOK: E1DA Cosmos ADC - affordable high performance measurements for the audio hobbyist!

As you can see in the picture above, I have one of Ivan Khlyupin's (aka IVX) Cosmos ADCs. It's not available yet on the market, so watch for when it's released from E1DA in the days ahead. Thank you Ivan for reaching out and sending this unit for me to use!

[If you're wondering about the E1DA name, as explained by Ivan, it comes from the pronunciation of "Ivan" as sounding like "E1" in Russian as opposed to the Americanized "Eye-Ven". "DA" as in "dah" ("да", "yes") - so it means "Ivan Yes".]

While this unit is one of his builds for external testers, I suspect that it should be much the same as the final product when available hopefully later this month. Obviously there could still be some changes with the final production release.

I think the price is slated for around US$150. Also, in the days ahead, E1DA will be releasing the "APU" (Analog Processing Unit) that can complement an ADC for measurements with the ability to notch out the 1kHz fundamental among other features allowing even more accurate measurements of very high performance gear. And there's also the Cosmos DAC coming as well to complete the "trinity".

For today, let's have a peek at the Cosmos ADC. Let's explore how to get it going, some of its features, and although still early days, we can take a quick look at measurements with this tool, with some DACs I have here.

Archimago's Musical Performance Track (AMPT): Standard test track for listener evaluation of source playback. [RME ADI-2 Pro FS R BE, Topping D10s, D10 Balanced, TEAC UD-501, Squeezebox Touch recordings.] Loss of RMAF, Bluetooth aptX Lossless. PS: Topping D90SE.

Over the years, we've seen websites, blogs, and videos try ways to demonstrate the sound of a hi-fi device or for the adventurous, even try to convey the sound quality of listening rooms. For example, there are binaural recordings at audio shows, soundroom demos, speaker comparison samples, etc. This is not an easy task because high-fidelity is about nuances and slight variations; not wholesale "obvious" differences for many devices like DACs or high performance amplifiers. Unlike what you might read in audio reviews, assuming you have a decent DAC already, a replacement would be unlikely to result in obvious changes in characteristics like bass response or claims that jitter effects are somehow obviously audible! Sorry folks, a lot of that kind of talk is just fantasy.

While it is convenient to view and listen to typical YouTube clips, I think we can all appreciate that sound quality would be highly affected by: the recording microphone, room acoustics, set-up quality, the lossy audio compression from YouTube among others that I may have missed. Dissociating the effect of the different components would be impossible. And obviously any time you use a transducer to convert the sound pressure into electrical signal (ie. speaker, microphone), there will be a significant reduction in resolution if we're trying to determine the effect of something like a DAC!

Then there's the issue of what music is being used? Is it music that audiophiles have general access to? Is it material that audiophiles/music lovers would even generally listen to? Obviously this bit is very subjective but I think there's something to be said about esoteric test material that might be recorded amazingly well, but just not adequately popular to have "mainstream" level acceptance. When "subjectivist" audiophiles complain that test tones are artificial and synthetic, is it that much different from listening to a handful of albums that barely anyone cares about? ;-)

SUMMER MUSINGS: On the dreaded "Digital Glare" in audio, and conversely, exaggerated analogue evangelism.

A reader E-mailed me the other day asking about what I thought of the dreaded "digital glare" because it was mentioned by a "more subjective reviewer" he was also connecting with.

Basically, I don't believe "glare" exists as a generalizable phenomenon that is somehow special to digital audio. Rather, my guess over the years on how some audiophiles started using this term is that many of the early CDs (not necessarily subsequent remasters) did sound overly bright and harsh. As much as I love the music on The Nightfly (Donald Fagen, 1982), Dire Straits' Brothers in Arms (1985), Dead or Alive's Youthquake (1985), OMD's Organization (1980, 1985 CD release), Culture Club's Kissing To Be Clever (1982, ?1984 CD), ABBA's The Visitors (1981, 1983 CD release), despite excellent dynamic range, the sound of these albums are just "bright", too "thin", a bit "glassy". Perhaps some of this also has to do with the synthetic instrumentation and studio techniques of the time.

SUMMER MUSINGS: Room EQ Preferences - Vintage Spendor SA1-like curve, Hang Loose Convolver (HLC), and the increasing relative importance of software.

Getting ready for an evening of digital filter evaluation!

I mentioned a few month back in my Spendor SA1 (1976) review/measurements that I really enjoyed the sound of these classic speakers!

While it would not be possible to exactly replicate their sound - these are complex devices with all kinds of unique properties including distortion idiosyncrasies and unique radiation patterns - to some extent, we can try to replicate the frequency response via DSP.

These days, we have the technology available to modify the sound we hear in the soundroom without great difficulty; the trick is to make sure the sound has improved, at least subjectively, when we add things like EQ or applied other signal processing.

Although some (typically more traditional) audiophiles will speak of maintaining "purity" of sound with minimalistic set-ups, if one is a contemporary technologically astute music lover and audiophile, especially one already using complex streamers, computer gear, networked libraries, I don't believe there should be any fear in going all the way using high-quality DSP to shape and adjust what we hear. In fact, from the frequency response perspective, we can "emulate" almost whatever we might want depending on the flexibility of the software used.

MEASUREMENTS / REVIEW: Topping D10 Balanced (D10B) DAC. Simple, no-nonsense USB DAC, excellent balanced sound quality.

Last month, I published on the Topping D10s DAC which performed excellently for such a small, USB-powered device. Fantastic price to boot!

Today, let's have a look at the newest sibling in this line of DACs released in July 2021 - the Topping D10 Balanced (I'll just call it D10B for short). As you can see in the image above, the contents in the box are similar to the Topping D10s, with manual (including measurements), pamphlet with various other Topping products listed, generic USB A-B cable, and for this model a couple of TSR-to-XLR male-male adaptors.

At <US$150, this is certainly still inexpensive. And as the name suggests, this baby is capable of balanced analogue output. Balanced transmission provides improved common-mode noise rejection and this should result in quieter analogue output including rejection of potential issues like mains hum in the signal.

I bought this DAC through the usual retail channels; no relationship with the company.

SUMMER MUSINGS: No... Not all amplifiers sound the same (but many do! ;-).

With both my Class D Hypex nCore NC252MP amp and linnrd's Class A Pass/First Watt SIT-2 in my sound room a couple months back, this allowed me to switch reasonably quickly between them to listen. You might be wondering about some comparison comments on how the amps sound. Certainly much has been said in the press about sonic differences between amps over the decades, but relatively little has been shown with measurements in an actual room using what comes out from the speaker.

First thing I'll say is, "No, not all amplifiers sound the same!". This should be obvious actually when looking at the objective measurements of the amplifiers and what they mean if we extrapolate the results to a known system.

Like I said, it seems uncommon to see measurements "in situ" with amps connected to the same DAC, preamp, and speakers to show differences. To demonstrate the differences in my room with my speakers, I set up the miniDSP UMIK-1 microphone in the room like so to run some sweeps and tonal FFT's for comparing:

Mega-taps upsampling: Remastero's Pan Galactic Gargle Blaster (PGGB) software. (Broadly on audiophile software & the noise boogeyman.)

This article came about after I received an E-mail from an audiophile friend who saw this Audiophile Style thread in praise of "math and magic". It links to a piece of software by a site called remastero, and the program itself is called "PGGB" (Pan Galactic Gargle Blaster), obviously referring to The Hitchhiker's Guide To The Galaxy with the main author named Zaphod Beeblebrox (who in the book is also the ex-president of the Galaxy). Cute, and of course the number "42" features prominently here and there.

In the past, we have talked about "audiophile" software that supposedly affect sound quality. Years ago, we talked about bit-perfect players (Windows, Mac) and really how "bit-perfect" is simply "bit-perfect" regardless of what software is used. We discussed questionable programs like JPLAY. Then there are the OS tweaks like Fidelizer. Neither JPLAY nor Fidelizer made any difference in my testing or listening.

That is not to say software doesn't make a difference at all. With the computing power we have these days, we can certainly perform highly precise filtering and DSD-PCM transcoding - like with HQPlayer. 

The idea with PGGB is that this is software that will take (in batch) various tracks you have and convert these to upsampled versions like 24/384 or 32/705.6 or even higher. In the process, applying very strong filtering (eg. on the order of >200M-taps sinc filter for some of the tests we'll run here, very impressive big number, right?). Furthermore, the website states that the software can apply settings for various levels of "transparency", apply HF noise filtering, uses noise shaping, adjusts gain monitoring for intersample overs, deal with convolution filters, and an apodizing setting. That's a bit of stuff so I won't promise that we'll hit on all these here. My intent is to at least have a good look at the foundation of the upsampling effect and the EQ function.

MEASUREMENTS: Topping D10s - an inexpensive high performance basic USB DAC with S/PDIF outs. And on "perceptibly perfect" DACs.

 

Hey everyone, I suspect many of you have already seen or heard of the Topping D10s by now (~US$100-110 at time of writing). It has been out since spring/summer 2020, a DAC released during the early pandemic.

Basically, this is an update of the Topping D10 which I reviewed back in 2019 with change to the DAC chip from the ESS ES9018K2M to the ES9038Q2M with improved specs - lower noise, higher dynamic range, etc.

I bought this through the usual retail channels as I'm planning to give the D10 away to a family member. Let's have a deeper look and consider the implications of this change in the DAC chip to the overall performance.

Apple TV 4K, 2nd Generation (2021, A12 Bionic SoC, 6th Gen Apple TV): A look and listen (to "Spatial Audio" on Apple Music)...

So guys and gals, let's jump from the lo-tech "audiophile boutique" passive AudioQuest JitterBug FMJ last week to talk about something hi-tech this time.

As I mentioned a few weeks back, I've been listening to some of the "Spatial Audio" music streaming off Apple Music these days. Easy to give it a shot with the 1-3 month trial period they're offering.

As I mentioned before, while I enjoy the content on headphones and can experience the difference Atmos streaming makes, as one who enjoys excellent high fidelity sound quality (ie. "audiophile"), the best, most natural way of listening to multichannel content is in the sound room where I have my multiple speakers set up. I have a modest surround system with the ELAC Debut 2.0 A4.2 Atmos speakers (previously measured) adding a bit of that height effect with Paradigm Signature S8 v.3 fronts, matching C3 center channel, full tower Studio 80 v.3 for rears and dual subs to make basically a 5.1.2 arrangement.

The trick with getting the multichannel content out to the room has to do with whether Apple Music allows the bitstream to pass through the playback device into the AV receiver that can handle Atmos. As I mentioned in that previous article, I can get the "bed" channels out (ie. 5.1, 4.0, etc...) using my wife's M1 MacBook Air running the recent macOS Big Sur release, but this is with the machine decoding the DD+ (E-AC3) + Atmos stream into 24/48 5.1 PCM sent to the receiver over HDMI.

For bitstream passthrough including the full Atmos encoding, at least at this point in time, the Apple TV works and let's talk about this box today for audio/home theater usage... As you can see above, I have the Apple TV 4K, Gen 2, 64GB here - this was released just recently April/May 2021 with the "A12 Bionic" 7nm SoC which actually was first used in the iPhone XS series back in late 2018. Certainly energy-efficient and plenty fast for non-multitasking media playback. If you don't need the storage, the 32GB model saves you US$20 - as usual, Apple has no SD card expansion for their devices. Internally, the machine has 3GB RAM.

MEASUREMENTS: Review of AudioQuest JitterBug FMJ. (And on Milind Kunchur's recent RCA vs. XLR paper.)

Hmmm... What does "LESS DIGITAL NOISE" actually mean? After all, noise that's bad enough to affect digital data will result in errors. Obviously, that would be very bad!

Normally, I don't review stuff like this because there's simply little reason to believe these kind of things do anything of value.

I know, this comes across as highly biased right at the start of a review post! But I want to be honest and I wasn't born yesterday so I know there are all kinds of claims in the audiophile world that simply do not pan out. Furthermore, I've had experience with the AudioQuest company (see the Dragonfly Cobalt / Red / V1.2 DAC review a few years back) and know that they have made claims which turn out to be untrue when tested.

Another admission going into this is that I was introduced to the AQ JitterBug back in 2015, and over the years I have seen other tests like the Audio Science Review thread from 2019. Having said this, I am happy to be swayed if I truly hear a difference or measurements show me that I should change my mind.

So, when a local audiophile friend bought the new AudioQuest Jitterbug FMJ ["Full Metal Jacket" - cute] (~US$60, released mid-May 2021) and suggested I borrow it for a week as he went on vacation, I figured it would be fair to give it a try and see if I can run some measurements to provide data to audiophiles at large on this update to the product. I promised him that I would give him my honest opinion.

MEASUREMENTS: 1MORE Triple Driver Over-Ear Headphones (H1707) with wired remote & microphone. And on Galen Gareis / Iconoclast Cables interview recently.

Alright folks, on the test bench this week is the 1MORE Triple Driver Over-Ear Headphones (let's just shorten name to 3DOE). If you've seen this headphone over the years (released around Christmas time 2018), you'll probably know that we need to clarify a couple of things.

First, they're not actually "over-ear" as in truly "circumaural" headphones. The earpads/cups are not big and unless you really have small pinnae, will sit "partially circumaural" with portions against the pinnae like supraaural designs.

Secondly, it's more of a "dual" driver design rather than "triple". There are 2 active drivers - a graphene-coated 36mm mylar dynamic driver, and a 10mm ceramic/piezoelectric driver for treble. The third "driver" is the passive "bass reflector", much like speaker passive radiators but inside a closed headphone reinforcing a certain amount of bass response.

The silver model like the one I have here is the graphene-coated version. There is also a gold-colored version out there which is a titanium driver without the graphene layer. I've seen comments that the sound is similar between the two versions. This one was bought through the regular Amazon retail channel (on sale for <US$150) and as far as I can tell, is the current model with an inline remote control plus microphone good for use with your smartphone.

SUMMER MUSINGS: Surround sound to the masses! In support of 3D Audio / Dolby Atmos in music streaming (Apple "Spatial Audio")...

Hey guys and gals, this week I thought I'd take a break from measurements and observe what's going on in the audio, audiophile, and streaming world these days. I noticed some discussions and even concern among music listeners around Atmos and Apple Music's drive towards "spatialized" streaming.

As audiophiles, let's think and talk about this for a bit.

First, let's do a quick background recap so we're all on the same page...

REVIEW / MEASUREMENTS: Pass Labs / First Watt SIT-2 stereo Class A amplifier. [And Stereophile steps in with MQA yet again...]

 

Greetings all. For this post, as you can see above, I've got something exotic to review / measure here at chez Archimago. It's a Pass Labs / First Watt SIT-2 stereo amplifier which was made in limited quantities back around 2011-2013.

This amplifier comes with a nice backstory; that of the silicon carbide (SiC) "Static Induction Transistor" which you can read about here (aka V-FET). The thought is that these transistors behave in a "triode-like" manner, hence perhaps they will be able to convey a "tube-like" sound. Furthermore, this device follows the general audiophile philosophy of "simplicity and minimalism" (quoted from the manual) as principles that would result in a device sounding "good". As such, this amplifier has only a single SIT gain stage, operates in Class A, built with minimal components, employs no feedback, and as expected, accepts single-ended input only.

Online I found this user manual and Japanese product flier for those wanting a bit more information from the company. The cost of this amplifier when it first came out was around US$5000.

REVIEW / MEASUREMENTS: (Mass)Drop + HiFiMan HE-4XX Planar Magnetic Headphones (with Brainwavz XL Round Hybrid earpads). Maintenance if the earcup detaches.

Well, as I've mentioned previously, I don't really need more headphones. ;-) Alas, I could not resist picking up these minty Drop + HIFIMAN HE-4XX Planar Magnetics locally used at a price I could not refuse! I also love how they look with the classic headband. The matte "midnight blue" color looks like a dark charcoal with a subtle powder bluish tinge.

I know there have been different opinions on the build quality of these headphones. Some of the early units had issues with right-left imbalance, driver failures, and broken hinges. According to this post, it looks like replacements with serial number 5XXX have many issues fixed. My unit here has serial number 57XX.

The hinge where it interfaces with the headband feels robust on this unit and I think the build quality is very good. The steel gimbal and metal sliders seem like they will be able to hold up to daily use. No complaints there. I did have an issue with the part interfacing the ear cup which I'll discuss below.

The stock cable is a little short for my taste at around 5'/1.5m (6' would be better for my desktop use). Notice that the cable is angled 90°, terminated with a 3.5mm connector which is fine for mobile use. I think a straight cable would have been preferred since most buyers would likely be using these open headphones at home almost exclusively. I like the soft, pliable nature of the cable although I have read some complaints that it can kink and fail. I don't think there's an issue, replacements are not expensive anyway.

REVIEW / MEASUREMENTS: (Anthony) Gallo Acoustics A'Diva Ti (~2005) & Nucleus Micro Speakers (~2000).

Hey ladies and gents, let's switch from discussing headphones this week and have a look and listen at some speakers.

You've probably seen speakers like the ones above over the years. These are the "iconic" Gallo Acoustics A'Diva Ti speakers from the UK. These specific ones are probably something like 16 years old and the 5" diameter A'Diva orb (with 3" driver) is in fact the larger of the 2 speakers from Gallo we'll be talking about today.

Here's the smaller 4" diameter (also 3" driver) little brother - the Nucleus Micro. Note that this is the "non-Ti" version which is from the previous generation, made around year 2000 with presumably a different driver. Unlike the stainless steel protective grille of the A'Diva, the fabric grille is easily removed for photography:

Modding the Dekoni Blue ("Arch-Mod5"). Streaming audio: Apple Music to be "true hi-res lossless" stereo with multichannel (Atmos) in June.

A couple weeks back, I measured the Dekoni Blue headphone which as I noted, is itself a "modded" Fostex T50RP Mk 3 planar-magnetic (aka "Regular Phase", aka "isodynamic") headphone. It would be completely remiss of me if in a review/discussion of the Dekoni/Fostex I were not to spend some time talking about modding!

Modding has an very long tradition in the 'head-fi' world and I think it's been generally recognized that the Fostex headphones are the classic headphones to perform surgeries on. Much of what I'll be talking about here will be nothing new to those deep into this stuff already. For more on modding, check out this Headphonesty article for a background.

To start, as always, we need a plan and a "vision". As I mentioned in the last article, the Dekoni Blue sounds pretty good for the most part, so my job isn't to change the performance completely, but to rather refine what is there. If a headphone sound highly objectionable, one should really just move on and buy something else! Let's review the measurements I published last time for the Dekoni Blue with the supplied earpads and see what we can try...

MEASUREMENTS: AKG Q701 "Quincy Jones Signature" (2012) & AKG K260 (vintage 1987-1988). And recent interviews with audiophile cable/power people [Shunyata / AudioQuest].

For today's post, let's have a listen and look at the two AKG headphone models above separated by about 25 years in age. On the left we have the AKG Q701 "Quincy Jones" Signature Reference-Class Premium Headphone which was released in 2011. I bought this one (I preferred the black rather than some of the funky colors like neon green) in late 2012.

On the right, we have a rather uncommon AKG K260 - first edition released in 1987-1988, borrowed from my friend linnrd locally. A later versions of this headphone was relabeled with the "Professional" name attached. There's also a Philips version from back in the day using AKG as OEM. This particular one here is used but still in good condition which I cleaned up a bit before more critical listening and measurements.

Notice the "AKG look" with the leather or faux-leather headbands and the thin plastic/metal semicircular arches up top.

REVIEW / MEASUREMENTS: Dekoni Blue ("Approved" Fostex T50RP Mk 3 mod). And the importance of the room for hi-fi reviews (Wilson Chronosonic XVX speakers in Stereophile).

As you can see in the image above and might know already, these are essentially Fostex T50RP Mk 3 headphones which have been out since 2015. In 2018, the Dekoni company (which makes aftermarket headphone pads and accessories mainly) decided to make a licensed version of the Fostex with their own earpads and blue esthetics - hence the Dekoni Blue (~US$250). If you want a little more background, here's Dekoni's "Short Essay..." on the product.

If you've used Fostex headphones before, I think you'll appreciate that the stock ear pads are thin and rather uncomfortable so upgraded earpads are mandatory for long-term use. When I got these, it was less expensive that a new Fostex + upgraded earpads.

MEASUREMENTS: Sennheiser HD650 (~2010-2012) and HD800 (~2010). A comparison of two "Reference Class" headphones, and a look/listen to the "Sennheiser veil / darkness". [Inexpensive 2TB SSD and inflation in consumer electronics...]

As you can see in the picture above, this is a bit of what the "box opening" looks like when you buy either one of these "Reference Class" Sennheiser headphones.

Much has already been said about the headphones being measured today. The Sennheiser HD650 was originally released back in 2003. Of interest historically, there was a fire in the Ireland factory back in 2004 so there probably are not many older pre-fire HD650's floating out there. Tyll Hertsens' article about the Sennheiser HD580/600/650 is a great summary and SolderDude has a ton of stuff on the HD650 on DIY-Audio-Heaven. SBAF has this "compendium" on the HD650 which I think covers everything... and more! Oh yeah, even NwAvGuy got one of these back in 2011.

These days, there's the Massdrop x Sennheiser HD6XX which would be the latest version of the HD650 discussed here, while the Sennheiser HD660S looks similar but has redesigned drivers.

Likewise, you already no doubt would have read about the Sennheiser HD800 over the years. These came out in 2009, sporting the large 56mm "ring radiator" driver (vs. 42mm transducer of the HD650). The HD800 has since been revised with the HD800S in 2016 (here's Tyll's take with mods discussions). Multiple reviews on Head-Fi. The HD800S sounds very similar to the HD800 to me.

For this post, let's look at measurements comparing the two and I'll put in my 2¢ on the sonic differences as I hear them.

Home Network: The ASUS ROG Rapture GT-AX11000 WiFi-6 Router & QNAP QSW-M2108-2C mixed 2.5GbE + 10GbE switch. (Internet jitter and "one number" audio objectivism.)

QNAP multi-gigabit switch being installed behind the basement home electrical panel.

Well guys & gals, it seems like every year, I'll post at least an article on computer networking.

I know, this isn't specifically audiophile-related but for us computer/streaming digital audiophiles, that computer network infrastructure we run at home is important and certainly being home-bound in the midst of the COVID-19 pandemic, a smoothly running network has become even more important for work, education, socialization and play these days.

So with both my kids now teenagers in high school, myself and the wife having to do more work from home, and the ongoing (exhausting) use of video conferencing, I figure I might as well optimize the system and hopefully forego thinking about this for a few years. ;-)

So today, let's talk about wireless, router features, and multi-gig wired home ethernet.

The top image is my new WiFi router. The 4lb, 802.11ax "Wi-Fi 6" capable, tri-band (2.4 + dual-5GHz), up to 160MHz bandwidth in 5GHz, DFS, 12-stream, 8-antennae, 1.8GHz quad ARMv8 64-bit cores, 1GB RAM, 256MB firmware, 2.5GbE-port, ASUS ROG Rapture GT-AX11000; from now on I'll just call it the "GT-AX11000".

REVIEW / MEASUREMENTS: Drop + THX AAA 789 Linear Headphone Amplifier. And on Audioholics' THX Onyx DAC/amp "review" with a dash of MQA nonsense...

With much of my soundroom and other parts of the audio system sorted out to my satisfaction these days, I thought it would be time to start paying a little more attention to the headphone side of things. As you can see, in the last few weeks we've talked about the AKG K371 headphone, and prior to that some discussions on impedance and power.

Prior to about 2013, I was very much into headphone stuff when the kids were babies and louder music playback was simply not an option. Thankfully this all changed when the basement man-cave became available! ;-)

When writing about headphones and reviewing, it's important to have a good foundation set-up for "reference" listening. This means I would need a good headphone amplifier on my desktop Workstation computer; one that would support and optimize playback of some of the more hard-to-drive headphones - those with challenging output impedances and lower sensitivities. In alignment with that goal, I have the Drop + THX AAA 789 Amplifier on my table these days as you can see above.

REVIEW / MEASUREMENTS: AKG K371 (closed-back, over-ear, dynamic driver) - An affordable, modern, standard studio headphone. (And on using the miniDSP [H]EARS rig.)

Hey guys and gals, the post here today will be on the longish side since this is the first time I'm writing a headphone review with some measurements. Best to take the opportunity to discuss the testing itself as well as product impressions.

As you can see above, today we'll be considering the AKG K371, an inexpensive (~US$120) "studio" 50mm dynamic headphone that's easy to drive, with a sound signature based on Harman research into headphone tonality - see this nice presentation from 2017 containing a review of the various research over the years.

I bought these headphones from the usual retail channels.

First let me show you some pictures of these particular headphones, and later, we'll get into measurements with the inexpensive miniDSP (H)EARS test fixture.

MEASUREMENTS: Melody Onix SP3 Mk. II (~2006) Class AB Tube Integrated Amplifier. (And it isn't "diminishing returns" on sound quality, often there are simply "no returns".)

Recently I was curious about trying a tube amp in my system and my dad who's into his vintage gear including some older tube devices offered me this amp to test out. It was time to take up the offer and have a listen plus put some tube gear on the test bench for a peek at the performance.

As you can see, for today's post, we have the Melody Onix SP3 Mark II which I believe was first released in 2004 for US$1000. This one I believe was bought in 2006. It's a relatively compact unit (12" x 8" x 13" or so), 56lb beast designed by Melody Australia, made in China. Over the years, there have been various reviews on this product from 6Moons (Best of 2005 list), Audioholics, Home Theater Review, High Fidelity Review among others. Here's the Melody company website. I think this model was discontinued by around 2010.

I've always liked the look of this box. There's a cage that normally protects fingers from the four large power tubes and individual smaller covers (you can see 3 on the right removed) that protects the 6 flanking tubes. Turn off the lights at night and it all looks very cool.

MEASUREMENTS / MUSINGS: Headphone impedance, sensitivity, efficiency, and amplifier output impedance. (And a quick thought on Darko's "All You Need Is...")

Some people have walls of headphones. Well the other day I thought I'd take out my little collection accumulated over the last few decades around the house, some of them used by the kids, and let's dump them on the sound room ottoman to have a look :-).

The majority are based on dynamic drivers with a couple of balanced armatures (Etymotic ER-4, 1MORE Quad Driver). I'm actually missing a few there that were in use that evening by others around the home - the Dekoni Blue (an officially sanctioned "modded" Fostex T50RP Mk 3) planar-magnetic, the AKG K371, and Apple AirPods Pro (wireless) which my wife had brought to work and "forgot" to bring home that evening.

I was curious about the impedances of these devices and thought it would be good to put together a summary article looking at this along with the power needed to drive headphones and correlating these characteristics with amplification.

Although I have spoken of the importance of mobile audio in the past, I really have been remiss in not putting enough emphasis on this trend or the importance of headphones in these blog pages over the years. Despite this, some of the most common E-mails I've received over the years have actually been about headphones. So let's make sure to incorporate some "head-fi" in the days ahead!

A look IN the Audio Precision APx555 B-Series. Thoughts on price and value in audio products.

From our "RETRO-MEASURE" of a 1980's cassette tape player a couple weeks back, let's make a 180° turn, look at some photos, and chat about "state of the art" performance gear this week!

A reader awhile back had the need to do some hardware work on the Audio Precision APx555 B-Series machine and in the process, was able to take a few photos of the innards, sharing it with me. The B-Series audio analyzer is the latest and greatest audio measurement device from AP. It was announced in December 2018 and here's a nice review from 2019 in audioXpress.

I thank my friend for sharing the images and helping me to understand some of what I'm looking at here. :-) There are no schematics publicly available of course so my comments will be in broad strokes and I'll leave it to the engineers reading this to examine deeper - click on the images for a higher resolution view.

I don't think I've ever seen pictures of the inside of these AP machines online but obviously the Internet is a big place so perhaps I have missed them. There is actually a good reason why you're not likely to see the insides of something like the APx555 - it's a calibrated device. It costs US$30,000+ to buy one of these. You'll be breaking 2 seals if you crack it open, that will also break calibration confirmation, and voids warranty the moment it's tampered with.

HOW-TO: Partial Frequency Correction with Acourate. Spotify HiFi coming and a look at the evolution of music sales/formats from 1980-2020.

Over the years, I've discussed the use of DSP room correction in these pages (here and here for the more recent articles). In Acourate, there's no single-step macro to tell the software to limit the correction to certain frequencies as far as I can tell. Instead, I saw this comment by Dr. Uli Brueggemann in one of Mitch Barnett's early articles (2013) hinting at a way to modify the inversion step of the filter to accomplish that task. This post is a step-by-step procedure for those interested in doing just such a thing with the software.

Note that even though I'm showing the process here, I'm certainly not suggesting that it's necessary whatsoever. In my listening, a full-spectrum room correction sounds great with the frequency-dependent-windowing (FDW) algorithm Acourate uses. Over the years with friends and family who have had the time to sit and listen, I have never had anyone complain that my usual full-spectrum filter did not sound better than the uncorrected sound in my room (and on occasion, I have measured and applied DSP to my friends'/family's sound systems as well to similar effect).

It's always great to have options though!

RETRO-MEASURE: Pioneer CT-S605 Cassette Recorder/Player (1989). On cassette quality / fidelity. Cassettes are "coming back"? And sentimental associations...

After the usual recent posts on DACs, DSP, speaker measurements, let's discuss something very different this week!

The other month, I was cleaning out some stuff from my basement and came across an old cache of "compact cassette tapes" which I had recorded back in my high school and early university years. I also still have a handful of old pre-recorded tapes that provided the soundtrack of those times in life.

Within this collection were some made in the mid-'80s until about the mid-'90s when affordable CD burners (~$500 I think around 1996) came on the market and I quickly shifted to making "mix-CDs" rather than mix tapes. In fact, I found some almost brand new tapes that I forgot I still had:

Left: Fuji DR-I standard Type I Fe2O3 "Normal Bias". Right: Maxell XL II Type II CrO2 "High Bias". Center: Sony Metal-SR basic level Type IV "Metal Bias" for "Digital Excellence" - back in the day :-).

MEASUREMENTS: Emotiva Airmotiv B1+ bookshelf speakers. A comment about Andrew Robinson's Fluance Reference XL8S video review and "Do measurements ultimately matter?".

Emotiva Airmotiv B1+: Comes with small manual, and some stick-on rubber footers in the plastic bag. Fabric covers in background.

Since mid-2020, I've been on a quest to find some replacement speakers for my computer desktop. Along the path, I've listened to and measured speakers like my old AudioEngine A2, the active Edifier S2000 MkIII, borrowed the Tannoy REVEAL 501a, the passive Fluance Reference XL8S, and of course tried the KEF LS50.

For this post, let's look at the Emotiva Airmotiv B1+ 2-way bookshelf speakers (US$229/pair), released in early 2020. Externally, these look like their predecessor, the Airmotiv B1 that first came out in 2016. I bought this pair direct from Emotiva in late 2020, arriving a little before Christmas.

REVIEW / MEASUREMENTS: HiFiBerry DSP Add-On with the DAC2 HD. A quick Roon 1.8 network/endpoint issue and remote access request.

This post is in many ways a continuation of the HiFiBerry DAC2 HD measurements presented last time with the devices sent to me by Doug Gardner for testing. For some background, this DSP Add-on is related to the BeoCreate project which was documented in this 2018 thesis in collaboration with Bang & Olufsen. The idea was to create an open-source system to allow consumers to build or update their own loudspeakers to be active devices. It looks like this DSP Add-On board leverages that software to do its magic.

As you can see in the thesis, the final BeoCreate product was a board which included 4-channel amplified outputs, digital S/PDIF input and output, DAC, and of course the programmable DSP subsystem. A Raspberry Pi could be added to provide network streaming capabilities.

For completeness, I want to mention that this DSP Add-On is also compatible with HiFiBerry's DAC2 Pro (~US$50-60) board. Notice that the DAC2 Pro is a less expensive DAC than the DAC2 HD and sports headphone out. The converter chip seems to be the TI PCM5122 (same as previous gen DAC+ Pro) based on what's listed in the specs sheet but I have not seen confirmation that is indeed the case.

REVIEW / MEASUREMENTS: HiFiBerry DAC2 HD HAT for Raspberry Pi

It has been awhile since I've measured any of the Raspberry Pi DAC HAT boards. In fact, it was back in 2016 that I got the HiFiBerry DAC+ Pro which I still use for basic streaming in the living room these days. Thanks to blog reader Doug Gardner, he sent me both his HiFiBerry DAC2 HD (~US$100) and DSP add-on (~US$60) boards you see above for testing. Doug was also very helpful in providing some background information and discussions on subjective impressions.

The DAC2 HD was released last year (around June 2020) and is based on the TI/Burr-Brown PCM1796 "Advanced Segment" DAC chip, an upgrade from the TI/BB PCM5122 found in the DAC+ Pro board. With the majority of my DAC measurements recently being ESS and AKM products, it's good to have a listen and look again at a TI/Burr-Brown-based product. Note that the PCM1796 is not a new component by a long shot! It has been available since 2004 I think (earliest specs sheet Dec 2003). My TEAC UD-501 and ASUS Xonar Essence One from 2013 were both based on dual PCM1795, a close sibling.

While I will be looking at the DSP add-on daughterboard (version 1.1, dated April 2020) more next time, for now, suffice it to say that this is based on the Analog Devices ADAU1452 chip, a 32-bit, 295MHz DSP.

RETRO-MEASURE: Spendor SA1 (1976) monitor bookshelf speakers (The foam tweeter ring tweak!? And on "Listen For Yourself!".)

 

For this week's blog post, let's have a look at another "retro-measure"! This time, I had the opportunity to listen and test out the early-version Spendor SA1 speaker which hails from 1976. Remember that over the years, Spendor has released newer versions of this "classic"; most recently around 2009 as reviewed here in Stereophile.

This is another speaker I borrowed from my friend linnrd and I spoke about it back in late 2019 when I visited his place. This time, let's have a proper listen with measurements and compare the performance objectively and subjectively!

The "Spendor Mini Monitor Type SA1" came out just before the classic BBC LS3/5A design around 1975. Like the LS3/5A, these monitors were designed to be used in mobile recording vehicles.

REVIEW/MEASUREMENTS: SMSL (S.M.S.L.) M100 Mk II Hi-Res DAC (USB, S/PDIF Toslink and Coaxial In, ESS Sabre 9018Q2C, below US$100)

 

[Disclosure: Over the years, I have measured and reviewed products I have either bought or borrowed from friends. The product discussed in this post was sent to me by Aoshida Audio for an honest review and impressions which I can keep to use. It would only be fair that I provide the free shipping and "lowest price guarantee" links to Aoshida if readers want to purchase this DAC or others discussed. Considering that a major part of my review process is objective in nature and standardized over many years, I trust that much of what I present will remain free of bias. Note that I will be selective of what I agree to measure/review of this nature - accessible and high fidelity products that might be of interest to readers, or more innovative devices will obviously be most appropriate for what I do.]

As you can see in the image above, today let's have a look at another very inexpensive DAC product from S.M.S.L. with high-resolution ability. Over the years, I have reviewed/measured other devices from this company including the SMSL A6 integrated amp, the SMSL iDEA DAC, and more recently I've been enjoying the SMSL SA300 Class-D desktop amplifier. These are examples of "accessible" audio products, well within the price range of basically any music lover, "audiophile" or not.

So it is with this DAC. The S.M.S.L. M100 Mk II currently costs less than US$95, needs little power, and accepts USB/TosLink/Coax S/PDIF inputs. As you can see, it's shaped as a rectangular prism. The size is smaller than the photo might suggest measuring at about 2 1/8" x 2 1/4" x 3 5/8" long, weighing around 0.5lb (250gm). The enclosure is aluminum with shiny plexiglass front panel; the package feel solid. Inside the box is an assortment of printed manuals in English, Chinese and Japanese along with a basic white USB-A to micro-USB cable.

Cable review: Monoprice Stage Right Series XLR - gold plated connectors, 16AWG conductors and differences between Made in China & Made In Vietnam... A few words about cable demos.

 

Behold... An XLR cable. How exciting. :-)

Although I've discussed speaker cables more recently, it has been ages since I've talked about interconnects. Nothing unusual about that - there's really not much to talk about - they're lengths of wire for low-voltage analogue audio signals! (The exception being AES/EBU digital over XLR cables.)

These days, cables are way past being "mature" products for analogue/digital pure-audio purposes. Of course this doesn't stop companies from trying to differentiate themselves and claiming to have achieved new levels of performance or supposed "significant" improvements in this or that and thus achieving "superior" audio quality.

What I think about "audiophile" cables is no mystery I hope - here's the summary post with various measurements compiled over the years that should cover most questions most might have.

For today's post, let's dive in and talk with some detail about XLR cables and these Monoprice Stage Right Series XLR cables (~US$20/6' length) which have become a standard for me here in the home recently whether for my sound system or for testing. To be clear, this is not a sponsored post and Monoprice did not send me the cables for free. I'll let you know if any product comes through this blog that is not directly purchased or borrowed from friends.

RETRO-MEASURE: Radio Shack / Realistic / Tandy Minimus 7 speakers (early 1980s, Cat. No. 40-2030A)

While the "latest and greatest" gear is always nice to check out, read about and measure, over the years, I've also loved the opportunity to examine some of the vintage, "retro" stuff from back in the day. For example, today we have a pair of all-metal, black, Realistic (Radio Shack / Tandy Corp.) Minimus 7 speakers from the early 1980's.

These were "classics" back in the day, found in many college dorms, restaurants, doctors' offices and available for sale at your friendly neighborhood Radio Shack for >25 years. For some more history, check out this page.

REVIEW / MEASUREMENTS: ELAC Debut 2.0 A4.2 Atmos Speakers

Well, with the pandemic of 2020/2021, one thing that has changed markedly in my family is that we're spending way more time watching movies and miniseries at home this past year. In fact the last movie I watched at the local "cineplex" was 1917 right before the Oscars on February 9, 2020. As such, 2020 has been a year of microwave popcorn, Netflix, Amazon Prime Video, Disney+ and the occasional UHD Blu-Ray played on my Oppo UDP-205 with the family on the sofa.

Wanting to use the Energy C100 bookshelf speakers elsewhere (see what I was doing here), I figured it was time to grab a pair of actual "Atmos elevation speakers". Not unexpectedly, the ELAC Debut 2.0 A4.2 Dolby Atmos Add-On Speakers were on sale before Christmas which you see in the image above.

MUSINGS: Noise, Jitter, Faith & The Autistic Fantasies of Digital Audiophilia ("For adults only?" Darko/Lavorgna conversation.)

Happy New Year dear audiophiles!

I hope 2021 brings with it many happy returns in the year ahead.

Note that this post will be of a rather critical tone... So if on an auspicious New Years Day you want something a little less confrontational, I suggest coming back another time :-).

Let's address something which I think many well-heeled digital audiophiles will probably have observed being discussed if they read typical "mainstream" audio magazines, online sites, or watch associated videos. It's the simple observation that when it comes to subjective-only reviewers discussing why something (often expensive!) can improve the sound of a digital system, it almost always comes down to 2 factors they want you to be concerned about:

1. Jitter

2. Noise ("electrical", RF/EMI, conducted/induced)