Saturday, 15 December 2018

MEASUREMENTS: Intel i7 PC and Raspberry Pi 3 B+ Audio Streamer - XLR / RCA, Noise and Jitter. Do digital transports / streamers really make a difference? Do USB cables?


This is a picture of the corner of the room where I performed the measurements for the post last week. Notice that Intel i7-3770K computer in the left corner I use for gaming? Within that box are 16GB DDR3 RAM, both a SanDisk Ultra II SSD and a recent 2TB Firecuda drive, plus a rather powerful nVidia GTX 1080 graphics processor which is what is driving the display on the 4K TV. Inside the case, it's all powered by a 6-year-old Antec 650W switching computer power supply these days. The computer is about 6 feet away from the TEAC UD-501 DAC.

Suppose I take a 16' USB cable and connected this computer to the DAC and compared the measurements with the low-power Raspberry Pi 3 B+ streamer... What do you think the result would be from the perspective of distortion and noise?

Before we start with results, here's the testing setup. Very similar to what I did last week.
Computer / Streamer (i7 computer or Raspberry Pi 3 B+ with JustBoom Digi HAT) → 16' generic USB cable or 12' generic TosLink / coaxial → DAC (TEAC UD-501) → generic 6' XLR balanced cable or 6' shielded RCA for unbalanced → RME ADI-2 Pro FS ADC → generic USB → Windows 10 measurement laptop
I don't think it'd be a surprise to anyone if I said that based on conventional "audiophile logic", the i7-3770K computer "should" be a terrible music player/streamer. Using plain ol' Foobar, Windows 10 ASIO driver for bit-perfect playback is nothing special. The computer's power supply should be rather poor for high-fi audio, and that GTX 1080 graphics card would make the noise even worse. Furthermore, shouldn't HDMI 2.0 be rather noisy, hooked up to a 75" 4K/60Hz TV sitting about 2 feet from the DAC?!

Let's see what the RightMark 24/96 results taken from the TEAC DAC's XLR output look like compared to the low-power Pi 3 with USB output or using the JustBoom Digi HAT...

SPS = Switching Power Supply for the Pi, Bat = RavPower 22000mAh Li battery, Wi = WiFi, Eth = ethernet, Scr = touchscreen ON
The two columns on the left are the Pi 3 and i7 computer connected to the DAC using USB. The two columns on the right are the Pi 3 with JustBoom Digi HAT with coaxial and TosLink connections to the same TEAC DAC. Notice the difference between USB and S/PDIF. Composite graphs:



Notice particularly how the IMD+N sweeps dissociate based on the interface used. Whether from the Pi 3 or i7 computer, the USB interface resulted in lower distortion on the sweeps (as I mentioned last week, I suspect this is correlated to jitter with the TosLink > Coax > USB).

And if I overlay the i7 computer noise floor playing digital silence over the previous Pi 3 log tracings shown last week (the yellow tracing pointed to being the i7 computer)...


There's nothing bad at all! Within the audible spectrum, the i7 computer noise profile stayed below -140dB. No terrible noise spikes or unusual ultrasonic noise differentiating the i7 despite the fact that we're looking at a moderately high-powered, older CPU using a typical multi-rail PC switching power supply with a powerful GPU inside with no attention paid to software audio or OS optimizations.

Okay. What if we stress the computer's i7 processor, nVidia GPU and power supply with a heavy processing load? Surely there must be all kinds of electrical noise that gets generated and passed down across the USB cable to the DAC, right? The i7-3770K has a TDP of 77W and at full load, the GTX 1080 GPU sucks up to 180W!

For this next set of results, here's what my computer is doing in the background while we run the RightMark tests to the TEAC DAC:


As you can see with the Task Manager window, the CPU is running at 100% (Prime 95 64-bit "Mixed" Stress Test in the background), while I'm running the FurMark GPU Stress Test with the GTX 1080 graphics card sucking up "99.4% TDP" at 78°C after >20 minutes. Remember, this is all running at 4K/60Hz over HDMI 2.0 on an i7 computer while sending the audio digital data over to the TEAC DAC! That's about as extreme as one can imagine playing music on a computer... Obviously, no sane audiophile would be doing this while enjoying music. Considering how extreme this is, what does objective testing show?



Nothing to suggest more noise or distortion! Surprised? Of course we really should not be by this point after all the measurements I've shown and discussions we've had over the years since 2013. Once we control for pitch inaccuracies (highly unlikely with modern digital), temporal fluctuations (eg. jitter, typically well controlled with asynchronous USB), and the DAC manages to reject noise reasonably well, guess what... "Bits are bits" even with generic cabling :-).

And just to be really complete... Here's the i7 jitter profile under full load:


From my testing, jitter anomalies are primarily a function of the DAC and asynchronous USB interfaces have served us well, the J-Test looks great even from a 5-year-old DAC. 100% CPU and 100% GPU processing did not affect the J-Test when transmitted over asynchronous USB. I have listened to the system and it sounds just great. The only thing is that after a few minutes the CPU and GPU fans will rev up which of course is intrusive for high-fidelity enjoyment, this is primarily why I prefer a fanless solution like the Raspberry Pi.

Notice however that so far I have been using the XLR balanced output in my measurements last week and so far with this post. While the DAC in balanced mode appears resilient to noise, what if we now switch over to the unbalanced RCA output? What kind of noise do we now see while using the i7 computer compared to the Raspberry Pi 3 B+ "Touch" streamer?


As we know, RCA unbalanced outputs are noisier than the balanced XLR results on good equipment. To the left we see 3 measurements with the i7 computer connected to the TEAC DAC by USB; we have the XLR results, followed by playback through RCA without increased CPU/GPU load, and then the RCA playback under 100% CPU & GPU load. On the right side, we have the cluster of results from the Raspberry Pi 3 B+ connected to the TEAC DAC through USB with a comparison of the XLR output compared to RCA either with switching power supply (ethernet + screen on) or lithium battery (WiFi + screen off).

Looking at the numbers, it's clear that XLR provides lower noise level, lower crosstalk, and consistently less distortion. This can be seen on the graphs:


There's a slight 60Hz hum along with a few noise peaks picked up using the RCA connection (highest component at 180Hz, -122.5dB). The IMD+N sweeps show a difference between the RCA and XLR outputs. Scouring through the graphs, the only other interesting thing here with the RCA output is the 2 low level peaks we see in the noise level that sticks out when the i7/nVidia computer is under high load as identified with the red arrows. Otherwise, there's not much else to see!

So yes, we can say that a very busy and electrically noisy computer can add to anomalies in the RCA output when connected to the DAC by a USB cable... But let's keep in mind the magnitude we're talking about. To demonstrate the extremes, here's a direct comparison of the noise floor up to 192kHz between the battery-powered Raspberry Pi 3 and the i7/nVidia computer running at 100% load (WaveSpectra, 384kHz sample rate, 128k FFT points):


As per the red arrows, there are small amounts of noise at 8kHz (possibly exacerbation of USB PHY packet noise?), 16kHz, plus a little bit at 45-50kHz. I think the rational audiophile will look at this and just say "What's the big deal!?". Well dear audiophiles, as far as I can tell, despite all the hype made about the need for expensive and supposedly quiet power supplies, or benefits of computer optimizations, there's basically little difference between a low-powered Raspberry Pi 3 B+ and a power-hungry Intel i7 computer with high-power graphics card even with unbalanced RCA output in my system!


Remember, the 8kHz, 16kHz and 45-50kHz noise above from the i7 computer under full load is only found with the RCA output. Balanced XLR output was successful in keeping out the noise:

 

Summary:

Well then... Let's wind this down and draw a few conclusions based on the data:

1. If you're an audiophile who wants low noise performance, go for a DAC with balanced XLR analogue output (and make sure the rest of your system is up to par).

2. While my experience has been that jitter is rather inaudible, if you want low jitter performance, asynchronous USB is generally better than S/PDIF (TosLink or coaxial). Newer DACs like the Oppo UDP-205 and RME ADI-2 Pro FS have excellent S/PDIF jitter rejection so even this difference is minimal. The better your DAC, the more "bits are bits".

3. I remain skeptical of claims that digital streamer devices can affect sound quality significantly unless they are actually changing the data sent to the DAC. As per the tests today, we see that even a computer that's not "optimized" for audio with ostensibly "noisy" hardware does not actually deteriorate measured playback quality nor actually worsen the noise floor much at all even when put under a very intense processing load. Furthermore, this was tested with the 5-year old TEAC UD-501 DAC rather than newer and potentially better devices.

4. This continues to add to the evidence that "audiophile" computer-based digital "transports" do not make a significant difference to the sound. I cannot subjectively hear a difference either when I play music as I switched around the configurations while measuring. What's most important remains the quality of the DAC itself. In my opinion, other than the user interface, supported features or the "non-utilitarian" benefits like the esthetics and the "wow factor" of an expensive system, "high end" devices like the Melco previously discussed will make no appreciable difference to the sound quality itself compared to an inexpensive Raspberry Pi connected to the same "good" DAC. As usual, I would like to see evidence to the contrary and challenge the manufacturers of such products (Aurender, Auralic, SOtM, Sonore, Fidelizer, Baetis, Antipodes, Innuos, etc.) to demonstrate objective benefits from the DAC output using their products (please also identify the DAC used and under what conditions).

5. Having said the above, remember that there are indeed subtle differences we can see on objective testing but I certainly would not consider these significant in my system. Be reasonable with your set-up and there should not be any concerns. Obviously, do not do things like put your DAC in close proximity to a powerful computer as the DAC and any poorly shielded cables could pick up electrical interference (one example is the old measurement using my ASUS Xonar Essence One back in the day sitting close to the computer). Remember the importance of low ambient noise in your sound room when enjoying music among other things like room treatments and decent reverb time. EQ'ing and digital room correction make huge differences as well. Also, especially if you have a complex component audio system, make sure to address ground loops if you hear hum.

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

Well, the Christmas audiophile sales drive is in force now with "Best Of" lists, "Gift Guides", music recommendations, and advertisements dessed up as reviews on-line :-).

I noticed recently that the idea of audible noise and jitter from different USB cables is alive and well in late 2018... Here's Darko's take on the benefits of the Curious USB cable expressed as "the double trouble of electrical noise and jitter that you dropped US$350 on a USB cable...". Personally I would not drop more than US$50 on a USB cable, but I'm cheap in this way :-). Obviously, I'd love to see some evidence in light of the post today for either "troubles". For the record, the 16' generic USB cable I used in the tests today was the US$6.00 AmazonBasics USB 2.0! Remember also my USB cable measurements back in the day.

I noticed that at least he made some comparisons and claims that the Curious USB cable beats out the AudioQuest Carbon. Of course this is a "safe" conclusion and rather nondisruptive to the Audiophile Industry Nature of Things which seeks to correlate sound quality with MSRP because the Curious cable is about twice the price of that AQ Carbon. Considering the findings in this post, what then does it mean if indeed audiophiles like Darko are able to hear a difference between USB cables because of "noise" and "jitter"? Does it mean that they can hear below the noise level of the RME ADI-2 Pro FS ADC!? Is the equipment he uses so noisy and jittery compared to even an i7 computer and a 5-year old DAC such that I would have needed those cables in order to detect the benefits? If indeed the AudioQuest cable sounded worse than the Curious cable, does that mean there's something defective with the AudioQuest because even a 16' $6 AmazonBasics USB cable did not show any unusual noise nor jitter!? Is he even sure that noise and jitter has anything to do with the reported sonic differences? May I humbly suggest that last explanation to be the most likely...

Other than here, perhaps Audio Science Review, and maybe other objective forums, when was the last time you saw a magazine or mainstream audiophile web post show overlays of the noise level using different cables? When did you last see a direct comparison of jitter being different using various cables connecting the same pieces of gear? I certainly do not recall anything in the last few years even though a magazine like Stereophile routinely shows much more sophisticated measurements. Why are such basic claims never investigated? So many questions about the way things are done in subjective audiophilia land yet so few answers.

I don't think it's any surprise that manufacturers (especially of snake oil) prefer objective measurements be avoided yet IMO clearly this information can be very useful for consumers. I don't think it's any secret that things like cables have fantastic markups to the price and are potentially very profitable products. The fact that mainstream audiophile magazines do not do objective comparisons and "investigative reporting" IMO is simply a reflection of the influence of Industry sponsorship. At least to some extent, the "press" functions as the advertising arm of the Industry and certain rather straightforward truths must be kept hidden so that myths like "Expensive USB cables make a huge difference!" remain within the realm of the possible to drive sales.

Look folks, I'm not insisting that people should not / must not buy audiophile USB cables; enjoy the freedom to do so! Gift them as stocking stuffers to your audiophile loved ones. Savour the unwrapping of a beautiful set of cables on Christmas morning! But just remember to take a few moments to compare with a decent run of generic USB 2.0 and honestly consider whether you hear a difference. Remember, it's OK not to hear a difference.

As I have said before, we don't always have to buy expensive audiophile toys because they "sound better". There's nothing wrong with a nice looking set of luxury cables, just like there's nothing wrong with wearing a nice suit, Italian leather shoes, fancy cufflinks, or a meticulously designed wristwatch. Nothing wrong with being a proud owner of a $5000 set of cables! Be proud if that's how they make you feel! Of course, remember that if you don't feel there's good value in those cables, it's great these days as customers that return policies are quite good and one is free to exercise that option as well. One could always use the money towards good music in 2019 and I'm sure the artists and record industry would appreciate that as well.

Have a good week everyone. Hope you're enjoying some holiday cheer especially accompanied with great music. Gonna take some R&R time soon :-).

33 comments:

  1. Once again, you've nailed it Arch. If I may call you Arch ;)
    After working in computer hardware\software for 35 years I got a headache & dizziness when first researching configuration for NAS based playback. I'd been doing simple HD playback via USB drive into my Oppo.
    A lot of the reading I did for NAS got suspiciously over-complicated in my mind.
    You needed fibre cables, specialized little pcs for headless operation, special power supplies for everything, $$$$ cables & on & on &on. Now it's multi-hundred dollar audiophile hubs. Spinning HDs are noisy and too slow, SSDs aren't.
    Noise is the arch enemy in all of this and everything EXCEPT bespoke built components stink up the place with their gobs of noise.
    Coming from a time spent in working and then software I had a hard time believing this knowing what I do about the protocols involved. To put it simply, the old analog transmissions were noisy as hell, digital is quiet as hell and far more accurate in ensuring that what is sent arrives exactly as sent.
    I finally disconnected from a certain forum\site that specializes in computer audiophilia as I couldn't take the BS any longer & getting smoked the few times I posted for talking about measurements and the quantitative facts about data transmission. There was another member there who had a background like mine who posted far more often. I think he's gone too.
    Apologies for my life story regarding digital audio.
    Just like in the analog audio world, there are a lot of folks in the digital audio realm that are getting taken to the cleaners by this nonsense.

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  2. Oh hell. Should've reviewed my post forgot there's no edit feature.
    Spent in working should read spent in networking and then software

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    Replies
    1. Hey Douglas,
      Thanks for the "life story" :-).

      I hear you and certainly not surprised about the issues you've run into with certain forums and individuals in the forums. Realize of course that one thing the sorry MQA chapter of audiophilia has taught us is that there are most certainly "shills" out there who speak positively about questionable products (whether paid through financial transactions or possibly in other ways paid "in kind").

      Sadly, while the Internet is a wonderful place to get information and help, it also is a place where falsehoods and myths are easily perpetuated. When there are financial interests at stake, of course we can expect these entities to advertise their "preferred" beliefs.

      Yeah, don't worry about the complexities and nonsense around computer audio. IMO, they have nothing to show when it comes to "better sound" beyond just massive amounts of hot air and propaganda.

      Delete
  3. But Archimago, you do realize these findings contradict virtually everything about this subject written in The Absolute Sound, Stereophile, Audiostream, ... How could all of the audiophile pundits get it so wrong? :)

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    Replies
    1. Greetings Jim,

      Well, maybe the laws of physics are a little different here on the W. Coast of North America. Maybe generic USB cables and computer parts shipped here are made to an "elevated standard" than the stuff Stereophile and TAS gets in their offices and send out to their writers.

      I'm not sure, but maybe Rafe Arnott still lives in Vancouver. Perhaps he should just go out and buy himself one of our higher quality generic USB cables rather than whatever poorly shielded and bad quality cables Stereophile/Hi-Fi News/AVTech sends him when writing the AudioStream and InnerFidelity pages.

      As for John Darko. Sadly it looks like those German generic USB cables must be atrocious for him to prefer wires that cost 20+ times the price! Very unlike the typical high quality goods found in Germany, especially German-engineered devices... :-(

      Happy holidays! Hope you're blessed with high quality laws of physics and good generic cables where you are. :-)

      Delete
    2. I think all these measurements help to put everything in perspective and get the priorities straight.

      Regarding "audiophile streamers"; this week I stumbled upon a forum thread were people are moding a NUC to equip it with an JCAT "audiophile USB card" (based on an idea from https://www.computeraudiophile.com/ca/ca-academy/computer-audiophile-pocket-server-caps-v20/). I think I'm not going to bother 😉

      Another mod that seems to become more popular is installing an "oven-controlled crystal oscillator" (OCXO clock), as used in this "audiophile streamer" https://thelinearsolution.com/streamer.html. Any idea's on that?

      Delete
    3. Hey Geert,
      Yeah, I tend to avoid J-Anything after looking at the JPLAY software and noting the lack of any benefit, plus a bug at least back then:
      http://archimago.blogspot.com/2015/08/measurements-audiophile-sound-and.html

      Unless JCAT shows us what benefit this USB card brings, it's at least "Class B" snake oil IMO.

      Right, OC crystal oscillators. In principle these should be good for accuracy over temperature variations. Remember that years ago, I tested the TASCAM UH-7000 which also featured a "temperature controlled oscillator" (TCXO). Indeed it was excellent and showed great low-level jitter performance. However the power supply was noisy:
      http://archimago.blogspot.com/2015/01/measurements-tascam-uh-7000-usb.html

      IMO, even though the oscillator could be more precise as discussed in the WiKi for those interested:
      https://en.wikipedia.org/wiki/Crystal_oven

      What's the point for audio? Is anyone going to be able to hear such microscopic differences?! The level of accuracy would be important in MHz and GHz systems, GPS precision, etc... But in audio equipment and with ears that can perceive typically lower than 20kHz? I would not lose much sleep around this :-).

      Delete
    4. One more thing.

      Other than some temperature variation as the device heats up, I trust nobody would be listening to their equipment in a room with any serious temperature fluctuations to worry about the crytal's thermal expansion! :-)

      Delete
  4. "rather nondisruptive to the Audiophile Industry Nature of Things which seeks to correlate sound quality with MSRP because the Curious cable is about twice the price of that AQ Carbon" is primo shade.

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  5. "hearing" the sound quality between ethernet cables and usb cables again...

    Imagine someone gets a fantastic idea for an audiophile USB thumb drive!

    "When your precious digital audio files are stored and reproduced from our UtramusicMagicUSB drive, one can immediately hear the clarity and naturalness that was until now locked and hidden away in your music! The timbres get brighter, the lows are so much tighter now, but don't take our word for it, check out the independent review here.

    UtramusicMagicUSB comes in three flavours:
    8GB - $250
    16GB - $350
    32GB - $600 (best buy)

    Get yours today, and don't forget our other must-haves for that sweet flawless sound from your digital system:
    SuperUSBDeblurer pass through dongle - remove that nasty jitter and ensure bit-perfect audio passthrough through all your interfaces (recommended one SuperUSBDeblurer per every usb port you use - recommended with UtramusicMagicUSB - hear the difference for yourself!)
    EsotherNET Diamond - worlds first CAT10 ethernet cable, now with SoundWizzzard directional bi-powered connectors - recommended for all your MQA audio
    CrystalizerPRO - losslessly convert your mp3 files to DSD and enjoy and bring a new sound dimension to your music collection!

    ReplyDelete
    Replies
    1. At this point satire is alarmingly close to reality...

      Delete
    2. UltramusicMagicUSB stick eh?

      Actually, remember Sony did something like this with the "audiophile" SD card back in 2015:
      https://www.theverge.com/2015/2/19/8068465/sony-memory-card-premium-sound-sr-64hxa

      I remember making a note of it back around then at a time when Neil Yound and the PonoPlayer hype was building:
      http://archimago.blogspot.com/2015/03/musings-audio-quality-various-formats.html

      Man, don't give the Industry any more ideas :-).

      Delete
  6. The problem is that audiophile industry tries to solve with new and very expensive equipment basic problems that can occur in some cases. Of course, when the same playback chain is done OK, needn't occur - and this is proven within this great blog, that digital audio can be done right within reasonable budget and we needn't buy expensive gear.

    For example with USB playback we can have these types of problems

    a) noisy USB power on the port that we have selected. If this is true, it can affect the DAC especially whe it is USB powered. If it is so, we can use different port, or use well- powered USB hub, or (preferably) use powered DAC.
    b) too many devices on one USB hub. Especially low speed and full speed (USB 1.1) devices can make problems since they need transaction translator (TT) and some hub (internal or external) have single-tt solution, therefore the latency on that usb hub can increase. Solution is to put USB 1.1 devices on one hub (group of ports that belong to one hub) and USB 2.0 devices on second hub. On the other hand, USB 2.0 and 3.0 devices mix much better, since although they are in the ports of one USb controller it has acutally two hubs and contacts lanes - for 2.0 and for 3.0.
    3) bad implementation of SPDIF or USB transport - have been more frequent in the past. If this is the case we must change the component that is wrong or not compatible.

    USB regens and special cables at best correct one of the things above. When the playback chain is done right, we do not need them.

    So it is nice to be assured than digital playback CAN be done right without very expensive gear, it is our task to realize it within our equipment :-)

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    Replies
    1. P.S. Usually USB 3.0 ports provide better power, since they are USB 3.0/2.0 combined and USB 3.0 has higher power limits (0.9A), therefore voltage regulation must handle higher requirements. So if the USB-powered DAC is not working well in USB 2.0, we can also try USB 3.0 if it is available on that device.

      Delete
    2. Hey Honza,
      Good point with the USB comment and USB 3 hubs/ports.

      Happy holidays!

      Delete
  7. Somewhat off-topic, but I'd love to see some objective, non-sycophantic reviews of these: https://www.vandenhul.com/product/the-extender/
    I particularly enjoyed reading the technical specs.
    Apologies if these have been mentioned before.

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    Replies
    1. LOL.

      Oh yeah... I'm these "Extenders" are the real deal. van den Hul must be really desperate for business or something to put it out like this!

      Delete
    2. I participated recently to a discussion in an Italian Facebook group about the Schumann resonators. The "Extender" seems like one of them (this one: https://www.amazon.com/Resonance-Ultra-low-Frequency-Generator-Relexation/dp/B07D52SRDD/ref=sr_1_3?ie=UTF8&qid=1545919494&sr=8-3&keywords=Nobsound+Schumann+Resonance is certainly less expensive).
      I learned from the creator of OSMO (a more refined version of the mentioned oscillator) that he created it working with neurologists on the influence of the slowly oscillating magnetic fields on the Theta waves in the brain.
      It was not intended for Hi-Fi, but some audiophile listened to it and the hype started.
      A more detailed discussion is on https://www.remusic.it/IT/ReMusic-intervista-AP-Design-c9822c00. I hope that your web browser translator shall do properly the work.

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    3. Please read "listened to it" as "listened music with the OSMO turned on".

      Delete
  8. Totally OT, but I noticed in the pic headlining this article what looks to be an
    Emotiva XPA-1L monoblock amp.

    Are these in current use? How do you like them?

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    Replies
    1. Yup, these are still in use for sure!

      Sounds excellent and in fact measured quite well a couple years back when I put it up against a rather expensive Vitus Audio amp:
      http://archimago.blogspot.com/2016/12/measurements-what-does-us500watt-stereo.html

      I like the low noise and clean undistorted sound. Fun to be able to try out the 35W Class A mode although AB is totally fine without wasting electricity or heating up the room unnecessarily.

      Delete
  9. Holy shit!
    Thanks for the link, Allan.
    As far as I know, Arch, you're the only site I've seen anything other than superficial marketing previews of this amp.
    Thank you

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  10. Thanks as always Archimago. I'm having a little fun right now. I've recently moved to a much smaller house and decided to use my "All-In-One" desktop setup to also run my 2 channel setup. When I hooked it all up I immediately noticed a "hum" when there is no signal and the amps turned up to "11" (no harm for Spinal Tap references). The ame async USB fed by WASAPI through the same cables with either of my "audio dedicated" laptops yields no such hum.

    With my laptop I went into BIOS and disabled all but the services needed for audio, but I need my All-In-One to be useful for other things. I've ordered some ferrite beads and will try those first this weekend.

    The point for me is that with computer audio the weak link isn't the cables, it isn't the outboard DAC (if designed in the last couple of years), instead it's almost always the computer. Adding a couple of beads isn't too big of a deal but if that doesn't get it I'll just have to settle for putting my audio laptop back in play.

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  11. Why would you not analyze the square waves at 100 Hz and 1000 Hz using both “transports” into the same dac? If the results are the same then your tests above would be enough, but what might you discover if the square waves are different ? Just a thought

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  12. Thank you for sharing this knowledge and fighting audiophoolery!

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  13. Darko comes across as an amicable man, but is a shill all the same. In the guise of a cool "music-first" audiophile, he serves as an industry mouthpiece. And why not? The free gadgets keep flowing in, he's at the center of attention and privy to future releases and trands.

    When it comes to Darko, caveat emptor should be practiced.

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  14. Hi Archimago - it's a great BLOTspot you've got here, a great source of useful information.
    I have just today published a page about building a Raspberry Pi Streamer, and it references (extensively) to your pages here.
    Please see: http://www.cfuttrup.com/touch_upgrade.html
    /Claus

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  15. Very useful “buyer beware”. Wish it had been here to read two months ago. It might have saved me buying a Core i5 headless fanless music server when I already have a perfectly good Windows PC with Intel core i7 mb! I was seduced into buying the little core i5 Linux Computer because I was told noise at my desktop was so bad. And of course I have to buy a linear power supply for the Linux instead of a SMPS, because the latter is too noisy! Hmmmm.....
    My big computer is at one end of the house, my main audio in the living room at the other end of the house, so based on archimago testing, I should have no meaningful noise issues. Nor should I have even at the computer, where I do have a high quality tube amp and very lovely sounding Spendor speakers. Hopefully 3’ distance is sufficient.
    But measurements be damned at some level. I can easily hear that the music coming from my name brand server sounds better than that which comes from my little Linux server. There are almost no distinguishing differences in the audio chain they both follow from Ethernet input to speakers. So how to account for the differences?? So in spite of measurements, I feel compelled to chase better SQ for the Linux.

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  16. Please continue this great work and I look forward to more of your awesome blog posts. kh620

    ReplyDelete
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