Part III: Topping DX9 "15th Anniversary" Limited Edition DAC & Headphone Amplifier - DSD, S/PDIF inputs, headphone out, pre-out, and AMPT. And the desire beyond Perceptibly Perfect.

With Raspberry Pi 'Touch' streamer showing album art running RoPieee, and the Topping DX9 VU meters playing, this looks quite nice in the audio rack!

Let's finish up with the last installment of the review/measurements for the Topping DX9 "15th Anniversary" DAC (see Part I, and Part II previously). As we have seen up to this point, it's quite a unique looking DAC and the initial PCM measurements over USB2.0 look great as a modern hi-resolution converter. In Part II I noted that there was an issue with the 176.4/192kHz frequency response that Topping was able to correct quickly with a firmware update. I'll be using the latest firmware 1.23 for the measurements here.

Let's continue then to dive in and explore the objective performance with some of the other main features for this DAC.

EARLY LOOK (Part II): E1DA #9039S USB Balanced DAC dongle/headphone amp - DSD and performance under load. A few more words on the "need" for higher DAC fidelity!

Last week, I published Part I of the review/measurements on the upcoming E1DA #9039S USB dongle DAC/headphone amplifier. Already, we've seen that this ESS ES9039Q2M-based balanced DAC produces very clean, high-resolution sound.

As we continue, let's delve deeper into the performance of this little device. We'll have a look at some features like DSD performance and more importantly, let's examine the balanced amplifier output when subjected to headphone-like loads to see how well it performs.

REVIEW: E1DA #9038D6K Dongle DAC / Headphone Amp (Part II): Headphone Amp Power, DSD, Subjective Impressions, AMPT & Perfectionistic Tweaking!

A great sounding music listening station! (Samsung Galaxy Tablet, Drop+HiFiMan HE-4XX, classic Jacky Cheung cantopop.)

Okay friends, today we continue with Part II of the discussion on E1DA's #9038D6K portable DAC/headphone amp. Please refer to Part I last time for the general overview of DAC performance which already tells us about the PCM resolution of the device. The data from last time shows that for the price and size, this unassuming dongle is one heck of an accurate, high-fidelity, high-resolution digital-analogue converter.

This time, let's move forward with exploring other areas not yet discussed. Specifically, let's focus on resolution when under headphone-like loads, look at DSD performance characteristics, have a listen to the DAC, and given that E1DA is known to be tweaker/DIY-friendly (including making devices like the Cosmos line), let's also talk about what I would consider more "extreme" tweaking for the perfectionist audiophiles!

REVIEW: S.M.S.L. DO100 DAC [Part III - DSD, Subjective, AMPT Recording, and Conclusions]. And a very close look at the Topping D10 Balanced THD(+N) vs. Level graph.

As you can see, the SMSL DO100 displays DSD samplerate in the form of DSD64 (64 x 44.1kHz = 2.8MHz), DSD128 (5.6MHz), DSD256 (11.3MHz) and DSD512 (22.6MHz).

Okay audiophile friends, let's finish off the trilogy of posts on the S.M.S.L. DO100 DAC with some final measurements around DSD performance, let's talk about subjective listening impressions, and as usual, let me provide a direct recording from the XLR output for comparison with others I have done (as discussed here).

We'll then put this all together as final concluding thoughts on this device.

Notes on DAC DSD (1-bit PDM) measurements going forward...

In the early 2000's, we witnessed the battle over hi-res audio in the form of SACD vs. DVD-A. SACD, the brainchild of Sony, utilized a 1-bit Pulse Density Modulation (PDM) method they called DSD (an advertising term) whereas DVD-A had the ability to store up to 24-bit, 192kHz Pulse Code Modulated (PCM) digital audio data (multichannel up to 24/96).

From the beginning, there were concerns about this push towards 1-bit systems into the consumer space along with claims that 1-bit PDM should form some kind of archival foundation for music. There were critics include Lipshitz and Vanderkooy - see their paper "Why Professional 1-Bit Sigma-Delta Conversion is a Bad Idea" from the September 2000 AES. And the next year in May 2001, they followed up with "Why 1-Bit Sigma-Delta Conversion is Unsuitable for High-Quality Applications". Even Bob Stuart chimed in on the unsuitability of DSD for "high-resolution audio" back in 2004. This is no surprise since Meridian was firmly with DVD-A including developing the MLP compression system which subsequently has been licensed by Dolby and renamed TrueHD; it looks like Dolby and Meridian had an arrangement dating back even to 1998.

These concerns around fidelity and the unsuitability of 1-bit PDM as an editable format in audio production are why in the professional world, we see audio recorded and edited in 24/352.8 "DXD" and Sony's own "DSD-Wide" (8-bit/2.8MHz) instead of DSD64/1-bit "DSD-Narrow".

While this was playing out in the academic/professional arena, the advertising industry including the "mainstream audiophile media" championed DSD and published all kinds of flowery words suggesting how it sounded "more natural", or "analogue-like" compared to PCM. While I don't think we can put an exact date on when DVD-Audio officially died as a viable commercial product, I think by 2005 it was quite clear that hi-res physical formats were not going to be mainstream and DVD-A did not have the number of titles available compared to SACD. My sense is that the hybrid-SACD feature with both DSD and CD-compatible layers was a major differentiating factor that has resulted in still a trickle of SACDs released these days.

I'm bring this stuff up now as an extension to the discussions around SoX-DSD and the Philips Test SACD articles last year during my series on the Topping D90SE review because I've been thinking about how best to standardize the DSD test signals I use when testing. Different DACs tend to handle DSD playback differently and I wanted to make sure that my test signal parameters are at least somewhat in line with the music encoded on an SACD or maybe DSD128 download these days.

Miscellany: FlexASIO for 384kHz, Philips 2001 SACD/DSD64 test signals (thanks Black Elk!), and Roon network multicast. [And Coltrane's A Love Supreme Live Hi-Res, Music Industry Crystal Ball, Magic Quantum Fuses!]

A scene from The Simpsons 1996...

Hey everyone, for this week, let's talk about a few "miscellaneous" topics which I've either wanted to mention over the last few months or have just come up as interesting tidbits I think worth documenting but not necessarily large enough as topics in individual posts. The main topics are:

A. Instead of ASIO4All, we can use FlexASIO with the E1DA Cosmos ADC for 384kHz samplerate measurements in Room EQ Wizard.

B. A look at some "standard" SACD test signals from Philips back in 2001. With many thanks and great discussions with Black Elk.

C. Roon needs network multicasting. Check this out if you're running into network issues; I had some problems initially with my ASUS ROG GT-AX11000 and relatively complex home network.

 

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: A Look At HQPlayer 3.25; Filtering, Dithering and DSD Conversion.

Over the years, no doubt many computer audio users have heard or perhaps tried using HQPlayer Desktop from Signalyst for music playback. While there is a GUI for playback as well as a sophisticated network transport architecture, it's the upsampling and PCM-to-DSD features that are the program's claim to fame. There has been a good amount of talk about the sound quality of the upsampling algorithms and some swear by the sonic differences the program makes.

While admittedly I don't follow HQPlayer chatter closely, I don't recall reading about specific settings and what they do other than opinions about the sound quality. In this way, HQPlayer has been a bit of a mystery and I know some folks have had difficulty getting it running over the years. It has certainly been on my list of items to look into. In fact, back in early 2017 when I wrote about Roon 1.2, I mentioned installing HQPlayer but never got around to actually writing about it.

Well, after all these years, and now with the requisite pieces of hardware at my disposal for a more thorough evaluation (reasonably fast CPU/GPU system, ADC capable of >192kHz, DAC capable of DSD512), it's time to have a peek "under the hood" at what it does...

MEASUREMENTS: Oppo UDP-205 DSD Playback (DSD64-DSD512), and PCM 768kHz. Plus CES2019 coverage thoughts...

Alright guys and gals, it has been months since I completed the set of measurements of the Oppo UDP-205 last year (here, here, and here).

In early December, David M wondered how the Oppo performed as a DSD player as I had neglected to measure that.

Over the years, I have measured DSD output performance but remember that this is a little bit of a pain :-). To obtain some results for comparison with PCM in RightMark, what I typically do is take the test signals (originating in 24-bit PCM), convert to DSD using software like Weiss Saracon, and then play back the DSD file through the DAC into the ADC which of course takes that analogue output resampled back into PCM for analysis. Doing this understandably adds other variables to the measurement system which should still be minuscule. Over the years, I have looked at things like PCM-to-DSD converters (here and here) to demonstrate that the conversion programs do have an effect as one would expect with different resampling and modulation algorithms.

HOWTO: Integrating WavPack 5-compressed DSD into Logitech Media Server (LMS).

piCorePlayer streaming WavPack-compressed DSD128 (1-bit, 5.6MHz) to TEAC UD-501 from recent nightly version of Logitech Media Server 7.9.1.

As I mentioned last time, it's great to see that DSD compression and metadata tagging are available in the form of WavPack 5. Starting from the post by michaelvv on the Squeezebox Forum, I decided to spend more time on getting WavPack-DSD working in LMS and managed to get it working quite stably installed on a Ubuntu Linux (currently 16.04 LTS) virtual machine in the Windows Server 2016 computer that serves as my repository of data, movies, and music. For a description of the initial software install, have a look at my HOWTO: LMS + BrutefirDRC Plugin post from last year. The hardware these days is my Intel i5-6500 server machine described here.

MUSINGS: On DSD, tagging, compression and conversion... Time for WavPack 5.

Many moons ago (back in 2013), I discussed DSD audio. While over the years I've talked about DSD from a a number of different angles (eg. JRiver realtime conversion listening, PCM <--> DSD conversion, conversion 2015, equipment DSD playback measurements like PonoPlayer / TEAC UD-501 / Oppo BDP-105 / Oppo Sonica DAC), concerns from that very first discussion about DSD still irks me these days!

The main issue is simply this: the lack of ability for gear and software to support both tagging and data compression when dealing with DSD. This IMO truly has been a ridiculous state of affairs for so many years! Despite years of cheerleading in the industry and even smaller sales outfits like NativeDSD Music already putting files out there for consumers, the relative inelegance of it all is rather silly.

As usual, I find it rather baffling that the typical mainstream audiophile press remains silent on deficiencies like this. To me, it is issues like these, while perhaps not "sexy" nor provides the press something to market to consumers, that when addressed can actually move the hobby forward. Unlike yet another megabuck product that provides a few minutes of eye-candy at best and affects the few, "infrastructural" changes can affect the many. Yet another example of the myopia of the audiophile press and an inability to muster any leadership in changing the industry and hobby in meaningful ways.

MEASUREMENTS: ASUS Xonar Essence One DSD Upgrade (Part II: NJR MUSES 02 "Audio Opamp Rolling")

As you may recall, a few months back, I posted on the ASUS Xonar Essence One and the DSD Upgrade Kit. That post was only Part I because the kit not only included an upgraded firmware EEPROM to allow DSD64 playback, but there were a couple of New Japan Radio MUSES 02 opamps in there to use as well. New Japan Radio seems insistent on marketing this MUSES brand of opamps for audiophile applications and certainly the price tag is consistent with the audio "high end" - we're talking US$45 per stereo "flagship" opamp (MUSES 01 and 02)! As a result, there are quite a number of fakes out there especially on eBay so make sure you get these chips from a reputable dealer if you're in the market.

On a side note, it's interesting that companies these days are using "replaceable opamps" as part of the feature set of devices like motherboards; even motherboard manufacturers like Gigabyte are in the act of selling opamp kits!

When it comes to the old ASUS Xonar Essence One, I figure why not perform a few measurements and see if replacing the LM4562NA opamps (US$2.00 a piece) I had in there with these expensive MUSES 02's made a difference; the company claims that there's a "Profound Musicality" benefit with the MUSES. As a reminder, I had put in the LM4562NA opamps a few years ago. The stock Essence One uses NE5532 (<US$1.00) so my results may not be the same as someone going from stock configuration to these MUSES 02's. Remember that "opamp rolling" is not uncommonly discussed on message forums. And there have been some excellent write-ups in the past. Like high-end cables, there are those who swear by the improvements they hear but looking around, I have not seen anyone publish objective results from a DAC despite all kinds of testimony.

Note that there are different positions I could place these MUSES in but basically settled on the Low Pass Filter (LPF) stage which potentially could benefit all audio outputs. (In diagram below: 3A - for RCA output only, 3B - XLRs, 4 - headphones only.) I really did not have any great desire to pull out and reseat various opamps to try different configurations so just plugged them into place and closed my DAC, running measurements before and after the surgical procedure.

So here they are situated on the PCB:

MEASUREMENTS: PonoPlayer and DSD Playback

Hey guys, just a quickie posting here for mid-week...

I was looking over the measurements over the last few months and realized I neglected to post results of the PonoPlayer doing DSD64 and DSD128 playback! So, instead of the data just sitting on my hard drive, I thought I might as well throw it out here for reference.

I don't believe I have seen anyone measure results of DSD playback with the PonoPlayer. I suspect a reason for this is that DSD was an "add-on" firmware upgrade released after the major magazines got a hold of these units for review. But then again, how often do you see measurements of DSD output quality?! I'm guessing that DSD playback was a "checklist" feature that some people wanted or it looked good for the company to support. Of course DSD is an acceptable input data format for the ESS SABRE9018K2M DAC chip (as it is with essentially all high quality DACs these days). DSD has been enabled as of firmware 1.0.5 back in February. For my tests, I'm using 1.0.6 from the May 2015 update.

MEASUREMENTS: ASUS Xonar Essence One MKI with DSD upgrade kit. (Part I: EEPROM)

Ahhhh... The ASUS Essence One! Even though looking back, compared to others I have listened to or measured, this DAC had its various imperfections, it has been my constant companion on the computer workstation. Through it, I have listened to hundreds of hours of music, edited my share of audio, evaluated pairs of headphones, and run various "experiments". Like an old friend, you get to learn (and at times even appreciate) the quirks. To this day, it remains my "workhorse" DAC. Why, you might ask?

Because it has 2 nice big volume knobs. One for speaker output, the other for the headphones... Simple as that :-).

If you look back at my measurements and review of this DAC back in 2013, you'll see that I generally liked it. With my perspective today, though I believe much can be improved (everything from channel/volume control balance [apparently fixed with later Essence One MKII edition which also incorporates the DSD feature], J-Test could look better, noise floor cleaner, etc...), it was the hyped up "symmetric upsampling" that was perhaps the most bizarre let-down. Imagine a digital filter that acted as a brick wall at 15kHz! Certainly made the DAC sound "mellow", but in a bad, inaccurate way...

Despite rumours of a fix to the firmware, nothing happened after I reported this anomaly. Until late 2014 by the looks of it. And I wasn't aware of this until this past month...

ANALYSIS: DSD Conversion Impulse & Spectral Display... Another few images for completeness!

A cool example of the "Spectral Frequency" display - from Adobe.

Okay guys, I actually wrote the text that follows 2 months ago before the Digital Filters Test. As happens sometimes, a post can get lost in the "draft" bin and later found. It refers back to the DSD-to-PCM analysis series from April:
ANALYSIS: DSD-to-PCM Conversion 2015 - Windows & Mac OS X
ANALYSIS: DSD-to-PCM 2015 - foobar SACD Plug-In, AuI ConverteR, noise & impulse response...

Consider this as part 3 of the 'trilogy' for this week as I continue to work on the results of the recently-closed Digital Filters Test.

------------------------

I was reminded recently by Wombat in his post here that we can have a look at the spectral frequency display as well when assessing sonic data in the audio editor. Also, Mnyb talked about the low-pass filtering in SACD players and what "standards" were used. Well, I don't know about the formal standards, but the first Sony SCD-1 SACD player back in 1999 had a defeatable analogue filter placed at 50kHz and according to the DSD Wiki, all SACD players were supposed to include this "optional" filter. I know a few people on audiophile forums suggest they subjectively preferred the filter be turned off.

ANALYSIS: DSD-to-PCM Conversion 2015 - Windows & Mac OS X

Impulse Response: One of the talking points from back in the day as a selling point for DSD... Yup! DSD can better reproduce a 0.000003 second "click". Source: Merging Technologies

I. Preamble

It is amazing how quickly another year has passed. About this time last year, I posted the first comparison of DSD Encoders and Decoders "shoot-out" of sorts comparing Weiss Saracon 01.61-27, KORG AudioGate 2.3.3 and JRiver 19.0.117 in terms of quality - both encoding and decoding fidelity using the RightMark Audio Analyzer software. The idea was to determine which of the three created DSD files from an original 24/96 PCM test signal and then decoded it back to 24/96 in a way where there was as little change in terms of distortion, flat frequency response, and lowest amount of added noise.

Perhaps not surprisingly, the expensive Weiss Saracon software sets the standard as the most consistent DSD encoder that resulted in the best output once decoded. The differences in decoding capability appeared to be very minor (questionable audibility between the 3) but objectively, both Saracon and JRiver 19 were on par and the free AudioGate 2 somewhat "noisier" in terms of the PCM output (I speculated this was due to stronger dithering algorithm).

Well, another year has passed in terms of software upgrades to DSD decoding and I was interested to compare the decoding capabilities as of late. We have brand new versions of JRiver and AudioGate now, plus I didn't get to test foobar with the DSDIFF plugin last year. Plus we now have DSD decoding on the Mac OS X available with XLD and commercially with DSD Master.

LIST: Suspected 44 or 48kHz PCM upsampled SACDs.

 The sentence says "supported by Japanese SACD manufacturer" (whatever that means!). An example of how the term SACD gets thrown around in cheap domestic and pirated Asian markets (this wasn't a true XRCD either)...

As I mentioned previously in my post on SACD (and DSD), there are a number of SACDs I have digitally ripped over the years that appear to be sourced from 44kHz PCM. This is of course the same sample rate as good ol' RedBook CD and therefore it's unlikely that these titles should sound any "better" than the CD release since the PCM-to-DSD conversion process will add some distortion to the original signal.

It's not difficult to detect these releases because of the "brickwall" loss of frequencies beyond 22kHz. Note that this list is of course unofficial and even though there's evidence that these come from 44 or 48kHz PCM, it's still possible they're from 24-bit data which could still be "hi-res".

An example of the 22kHz brickwall - Thelonious Monk's "Between The Devil And The Deep Blue Sea" off Straight, No Chaser SACD. Notice the typical ultrasonic 'noise shaped' SACD quantization noise from 22kHz up - filtered off in this case before 40kHz.

MUSINGS: On SACD & DSD audio...

SONY multi-page spread (with hybrid SACD 'RS500' sampler!).
Rolling Stones magazine, December 2003.

Okay, now that I have posted a number of measurements over the last months, permit me a moment to play "Speakers Corner" and talk a little about the state of affairs around DSD now in early 2013...

Firstly, remember that DSD isn't anything new. It's basically a digital format based on Delta-Sigma modulation which has been used in consumer digital audio since the late-80's and early 90's - remember those old Sony 1-bit and Panasonic MASH players from around that era? It was said that as the CD patents were set to expire, Sony and Philips decided to create a new disk format for the 21st century - hence the birth of SACD around 2000 using the "1-bit" encoding method instead of multibit-PCM carried on DVD-like disks capable of higher data capacity (multi-bit ended up being DVD-A of course). Sound quality was said to be better because of things like "100kHz frequency response", better noise floor and in time, multichannel. Of course in creating this new standard, copy protection was job one and they did a great job. I remember in 2004 visiting China and seeing pirated DVD-A's which were easily "cracked" soon after release, but not so SACD's.

MEASUREMENTS: Oppo BDP-105 does DSD.

Well, it's out...  The March 26, 2013 BETA firmware for the BDP-105 that allows native DSD playback from this unit's USB ports as DFF and DSF files on a USB stick. As far as I know, there are no plans currently to allow computer playback connected to the USB port as a DSD DAC.

With this recent development, I headed back to my friend's place to run a few more tests...

Here's the basic premise of what I did...

Using the freely available KORG AudioGate 2.3.1, synthetic 24/192 test signals from RightMark 6.2.5 were converted over to DSD64 (2.8MHz sampling) and DSD128 (5.6MHz) for testing. We soon found out that the DSD128 files created could not be played back properly by the Oppo (it would play but the DSD128 files had timing issues - played too slow). Presumably there is a bug here somewhere with the beta firmware or the AudioGate converter. As such, I was only able to test DSD64 playback.

The first thing done was to go through the Oppo's settings menu making sure there were no volume settings, bass management, etc. active. I believe if any of these are turned on, the DSD will get converted to PCM.

The hardware setup is similar to what I did with the original BDP-105 tests (only difference being use of the front USB connector):
Patriot Rage XT USB2 memory stick 16GB with test files --> front USB port of BDP-105 --> shielded 6' RCA --> E-MU 0404USB --> Win8 AMD X4 laptop

RightMark results:

The first 3 columns are the tests done in PCM mode at various hi-res sampling rates. These essentially measure <1 dB different compared to my original tests using the Oppo's USB asynchronous DAC. Nice confirmation of inter-test reliability.

The last column is with the 24/192 test signal converted to DSD with the KORG software. As you can see, it's almost the same. Note however that RightMark is calculating these parameters just within the audible spectrum between 20Hz - 20kHz (AES17 standard).

Frequency Response:

First hint/reminder of the DSD effect. There's some high frequency noise breaking through up in the 70kHz range. Otherwise, the curves are relatively comparable with -5dB extension out to around 40kHz for DSD and 50kHz for PCM 24/192.

Noise:

Demonstration of the DSD noise shaping through the Oppo. From 20kHz onwards, the noise level rises quite remarkably as you can see. It's all ultrasonic of course so unlikely to cause an audible problem and would only matter if this creates any strain on your amp/speaker system or if nonlinearities cause distortion in the audible spectrum.

Although also not a problem, notice the noise floor from about 12kHz to 20kHz is not as flat with DSD.

THD:

Another view of the ultrasonic noise.

Jitter:
The J-Test cannot be used with DSD of course. This is just for completeness. I've already shown previously that jitter isn't an issue with the Oppo...  Here's just what the 24-bit Dunn J-Test looks like going through DSD transcoding.

If we compare it to the PCM:

Note the loss of the regular modulation pattern. Basically this is telling us that the LSB in the 24-bit signal has been affected and effectively dithered over by the conversion process to DSD.

Analogue Output:
Lets now have a look at what a 1kHz -6dB sample looks like after going through the DSD process. What I did here was record a few seconds of a pure 1kHz test tone in 24/192 to have a look at the waveform zoomed in.

PCM 24/192 FLAC played back:

DSD64 KORG transcoded DFF file played back:

The high frequency noise in the DSD signal can be seen (you might have to click on the images to get a good look). Not a big deal in that this is not audible but a reminder that DSD64 cannot reproduce a simple 1kHz sine wave as smoothly as that produced by the reconstruction filter in the PCM domain.

Impression:
As I had hoped when I wrote that piece on the Pioneer DV-588A last month, here are some results from a device that performs "pure DSD" decoding.

Within the audible spectrum, DSD64 produced by the KORG AudioGate software looks good. Standard measurements like dynamic range, noise floor, distortion are all looking great and reminds us of the high level of performance the Oppo BDP-105 is capable of. I was disappointed that I could not get the KORG-encoded DSD128 test signals to play properly. I don't know if this is due to the KORG software or the beta firmware. Maybe I'd have better luck with Weiss Saracon if I had access to this conversion software... Oh well, maybe next time :-)

As a reminder, all the tests I've shown were converted from the 24/192 PCM domain into DSD64 and therefore will be subject to the limitations of the conversion software and PCM source (note that at 24/192, this is not likely a technical issue).

An interesting observation; even though the encoded DSD128 could not play, free downloads of demo material from 2L worked just fine on the Oppo! They sounded great with a wonderful sense of space, timbre, and dynamics.

Bottom line: The Oppo did a great job with DSD playback just like it did with PCM. Limitations of DSD are clearly seen (ultrasonic noise pollution mainly). From a purely technical perspective, within the 20Hz-20kHz audio spectrum, there's really nothing to differentiate all these hi-res formats. However, if you include ultrasonic characteristics, PCM is definitely cleaner.

Given the frequency response curve demonstrated, this KORG DSD64 conversion + Oppo playback system can likely be encapsulated within the parameters of a good 24/88 system.