USB VS HDMI for 2ch audio to receiver - Page 3

I am not asking if you would guess to get there. I asked, if you ran the experiment as suggested, would you be more inclined to follow it. You are taking the test away and then say you might do it. I didn't ask you about that.

But it is interesting that based on even less information than having run the test, you would follow that technique.

It seems to me there is such a fear that people would go and run the test, and post their outcome here. Why? How is that any different than random assertions that all modern gear sounds the same? How valid was that for Anry to say?

Did you challenge him to prove if he had tested all modern gear or even 1%?

Did you challenge him where in DBT definition it says that the result of the test extends to anything outside of that one and only test?

Did you challenge him that no DBT test that shows negative results, actually proves the opposite? In other words, that a negative outcome simply means the test did not find a difference. It can never prove that that a difference was not there. Just that in that test fixture and audience, nothing was found.

Bring forth even discussion and then I believe you are out there to save audiophiles from their supposed ignorance. As if they are that much less intelligent from the rest of us. They are not. Treat them with respect and even handedness and maybe, maybe they come around a tad . Otherwise, all of this smells like censorship and debating tactics to defend one's position at all cost.

No, the question was:

"Just curious if there are any differences in SQ between using the USB out on my Macbook and PC, VS using the HDMI out?"

Your answer was:

"Depending on the USB implementation, yes."

The question was not about measured performance, it was about sound quality. However, if we consider only the question for which actual reliable evidence has been presented, the proper answer would be:

"The answer depends on the implementation of the conversion from USB to analog audio signal, and the implementation of the conversion from HDMI to analog audio signal."

Your surreptitious changing of the question that the OP asked is yet another distraction.

Your unilateral changing of the OP question raised the spurious issue of how difficult it is to get audio out of an HDMI port that is as good as the audio from the same computer's USB port. Audiophiles don't care how difficult something is for a digital black box to do. Audiophiles care about whether or not the music sounds good. This is the 21st century and if something is difficult this week, it may very well be cheap and easy next week.

Furthermore, the evidence you've presented only considered jitter, creating the misleading impression that jitter is either the only area of potentially audible differences, or that the one that matter the most by an overwhelming amount. This is of course false.

You also falsely claimed that analog equipment does not have far more jitter than good digital equipment.

Wow and flutter in analog equipment is usually measured using a ca. 3 KHz tone. The very best Professional tape machines can achieve a weighted flutter figure of 0.03%, which is considered inaudible, *but for the fact that without weighting it would be an actual 0.3%.

Since jitter in digital audio gear is usually unweighted we must use the 0.3% number. This corresponds to a 9 Hz shift in the 3 KHz measurement tone. A 3 KHz tone has a period of 333 uSec. The 0.3% wow and flutter shifts its period by 1 uSec or 1,000 nSec or 1,000,000 pSec.

The best analog tape recorder has ONE MILLION pSec of jitter!

I know of no extant piece of digital audio gear that anybody takes seriously with ONE MILLION pSec of Jitter or even a small fraction of that.

Any piece of digital audio gear with less than ONE MILLION pSec of jitter or less, outperforms the very best analog tape recorders ever made.

You were excoriating digital equipment with a messily 3,800 pSec of jitter, yet you hove told us that analog equipment that actually has ONE MILLION pSec of jitter is not appreciably worse.

!!!!!!!!!!!!!!!!

BTW, the above information about analog jitter is from the Wikipedia article on wow and flutter, from which the sentence with an asterisk was paraphrased.

I think that intentionally making false claims about one's opponent's position is about as low as one can go with debating tactics, and so is pretending to read their minds.

There is no evidence anyplace that would even suggest that I think we should prove that all people hear any given difference.

This claim is simply a very low debating tactic that shows how despirate and confused some perosns involved in this debate are becoming.

The test is bogus, so I would ignore the results. You can't have less than no information.


Fear? I am not seeing that. Waste of time? Probably.


I'm not sure how what Arny thinks about a completely different subject is relevant to this discussion. He has his own views. I am not Arny.


These are all red herrings. This seems to be one of your preferred debating techniques. If you don't know what a red herring is, look it up at logicalfallacies.info.


You're not even aware of what my position is on the subjects you mentioned (which also happen to be largely irrelevant to this thread). BTW, I would choose USB or S/PDIF for two-channel instead of HDMI, simply because of the theoretical advantages of lower jitter of the former two alternatives. The difference is, I wouldn't try to make assertions that doing so results in audible differences unless I had actual evidence to back up the assertions.

The above paper is a conference paper from 2004 (not formally peer reviewed) and is contradicted by the following more recent (2007) peer-reviewed paper:

Audibility of a CD-Standard A/D/A Loop Inserted
into High-Resolution Audio Playback*
E. BRAD MEYER, AES Member AND DAVID R. MORAN, AES Member

Furthermore the following serious experimental glitch was described in the Blech paper but has been, until now concealed from the forum by Amirm:

"Because of its principle of operation, when a stop or
play command was issued directly or indirectly, the
DSD encoding in conjunction with the non-audio
format which was used for file storage on the multichannel
audio workstation caused a very brief, low-level
crackling sound. A similar sound also occurred in PCM
mode at similar moments, but was subtly different
sounding."


We thus have additional evidence that in the heat of battle, some debate participants are becoming confused and are in haste not reporting complete relevant information.

If the two are still somehow involved in employment together, there is a conflict that JJ would not cross, most likely.

You can certainly do that. Here is how I view it. All else being equal, I like to have my front panel and video circuits on. The former lets me see what the device is doing and the latter, lets me feel good that when watching say, a music video, my audio is not degraded base on existence of video.

So I perform the above test. I ran it on a number of SACD and CD players and found it to make a difference. So when using them as pure audio source, I turn off video and front panel. Some are nice in that they turn on their display when using the remote. That's nice. Others don't and I put up with it.

I also tested two high-end DACs and couldn't tell the difference between the font panel on and off. So I leave them on and can tell what they are doing as a result. This is good for example to confirm the sampling rate of the music you are listening through the PC.

So what you call less than no information, I find very useful in what I do with my hobby. I realize I can't convince you and that is cool. I write for everyone, even though I am just answering you .

I've never said any such thing, This is complete fabrication of Amirm's imagination.

We have yet another example of how some debate participants are becoming confused about the actual things that people are posting here or anyplace else.

JJ is an architect/CTO at DTS. I left Microsoft three years ago and have an entirely different business. We touch bases from time to time but that is it. There is no conflict of interest other than neither one of us wanting to spar with each other for the enjoyment of others to watch .

Indeed, I will not go back and forth with him as I do with Arny. I know JJ's point of view and he knows mine. I respect his knowledge immensely. He can down to depths I don't even know exists. I am hoping he also respects that I am not an idiot repeating stuff learned on a forum...

I read the paper and overlooked it, Arny. Comments Amir?


Even if not their former association might preclude such discussions. After all, teacher/student relationships don't always work out well later on. Look at the Kill Bill series!

Invoking Occam's switchblade, it is my suspicion that JJ simply has more pressing interests at this time. He got back pretty quickly with a brief reply this morning, but that's not the same as taking on this debate.

I think they have some good results there. That said, I have never tried to dig into it other than reading the papers. Others have though. See for the strong counter from Bruce who runs a recording studio locally: http://www.whatsbestforum.com/showth...ll=1#post39527


Indeed . I am determined to make sure that for the purpose of winning an internet argument, I don't damage a relationship with one of the people I really respect and hence my comment regarding not taking him on in the same manner.

If Arny can't handle this discussion by himself without JJ's help, how good can his arguments be?

Maybe it would have been a good idea to continue testing with those 4 individuals to see if they can perform equally well repeatedly, or, just a fluke, 4 out of 145 or so.

Thhis is explained by the paper:

"All four of these tests occurred within the final four
days of testing. By that point the testing schedule was
full, so unfortunately these individuals could not be
brought back for follow-up verification tests."

The paper goes on to minimize the effect of this flaw, but many remain unconvinced, partially because these particular results are contradicted by a later, peer-reviewed paper.

The fact of the matter is that many people including participants in the Hydrogen Audio form have been doing experiments like these for years, and they have also failed to come up with convincing positive results.

If you look at the history of audio, a refinement that is this elusive after more than a decade of testing by many independent parties generally falls by the wayside, and this has largely happened with DVD-A and SACD.

Blu Ray supports a cornucopia of formats and that's the future.

It is not contradicted. To contradict you must run the exact same experiment. That is not what they did. They are two different experiments, with two different setups, arriving at different conclusions. Who knows what would have happened to Meyer's test if the same four people in the 2004 study had showed up there.

This is the fallacy of your position. The tests are only valid in their own context. You cannot pull them out and apply them to something else. That is scientifically incorrect.


No you don't. I provide references so that they can read everything there. I said it before: all tests have flaws. You have examples of flaws in above. I linked to Bruce who analyzed some of the tracks Meyer used and found them to not have high frequency detail. Take your poison as they say .

The above also demonstrates how tough it is to perform ABX tests. The fixtures can impact the test. So it should not be surprising that there are not a hundred tests to use for this discussion. Of course, you are without proof that the four people voted the way they did because they heard the glitch. Possibility exists but we don't have data to convict.

And while quoting more from there article, here is a bit more:

"Evaluation of the test subjects’ questionnaires
showed that this noise was not consciously perceived by
any of them, and that the test does not lose any validity
on account of it."

And

"It should be emphasized, however, that the validity of
these four subjects’ results is not in any question
whatsoever, and the descriptive evaluation of this
experiment does not depend on any special explanation
of their scores."

So while I believe it was bad to have them have the glitches they did, as a tool to win an argument here, it works pretty effectively . It proves my point that just because a test is "ABX" it doesn't prove everything. Every test has a limit and this one did too.

More reading than I have time for. Maybe over the weekend.



I wasn't looking at it from the POV of winning. I also understand your position on damaging a relationship. Kind of like Mary Matalin & James Carville who I understand don't challenge each others very different political views. BTW, when she was asked how the two of them could happily coexist in marriage with such different political views, she replied something to the effect of, "What's important is that we believe in each other."


Now, you know that's not fair! Being skilled in debate does not mean one is necessarily right! Let's not forget that Warren G. Harding was a skilled orator as was a troubled painter in Europe.

Absolutely not true. Contradiction or not lies in the outcome of studies of the premise. If your idea was right and an experiment was flawed we'd never correct ourselves because we'd have to keep running the exact same flawed experiment over and over again.

You do seem to want to live in that trap!

I question your familiarity with the history of science, or at least your recollections of it.

Amirim, you were somewhat confused at first and now you seem to be totally lost in a muddle of false ideas. Take a break!

It is quite obvious that there was not good level matching between the "DSD Rip" and the analysis of the 2 players. Both the noise and the signal are far more intense in the "DSD Rip".

Thus his results don't show what he purports. Bad experimental design seems to be endemic among advocates of audiophile myths.

That it was. And I uniquely have data in that area so I spoke with confidence. For the last six months, I have been on a mission for the best path to extract audio quality out of the PC. As I described in another post, our shop is strictly standardized on PCs as the source. No $15K transport here. At least not yet. Don't see any reason why we can't extract superb quality out of a cheap PC.

I had lot of good test beds from cheap DACs to $35K processors and everything in between. I tested HDMI, Toslink, S/PDIF and USB both in async and sync variety. I also spoke to many people who had done similar tests.

The net result was what I stated: an excellent USB implementation beats all others including the might S/PDIF and HDMI implementation in the $35K Processor. And fortunately for frugal ones in us, the solution just costs $500. No audiophile dollars required here.

You should have seen the look on my team's eyes as I would swap out the standard connection with the async USB of my choice. They could not believe that fidelity was coming out of a PC.

The culmination of this effort was having a member of a major rock band and his sound guy coming over to visit. I had taken my USB adapter to use for another machine and they listened to HDMI from the PC. I was outside of the room as they listened to their music. Five minutes later they come out and say "it doesn't sound right."

I said hold on a minute. I run and fetched USB adapter and started to plug it in. His sound guy is watching over me and asks what the box is. I said it was a USB to S/PDIF converter. He said how is that going to make a change seeing it was yet another digital connection. I said I prefer to not say anything and just have him listen. He ignored that and asked once more why it would make a difference. I again said you should just listen and it may very well not make a difference. I could tell he was a bit annoyed at me but I just did not want to bias him one way or the other.

I let them go in the room again without me. A few minutes later he comes out all smiles and says how much better the sound was.

Now, we all know people who tell such anecdotal stories and it doesn't mean much typically. And at any rate, as a guy listening to loud music all the time, for all I know could have been deaf. So why did I tell the story? Well, I thought it was a good story to tell!!!

Seriously, for me personally it was rewarding to see a random positive comment like that. It could have easily gone the other way with him saying it made no difference or made things worse.

None of this is meant to have a scientific significance. But in the context of someone asking which one sounds better in a forum, I feel good about expressing what I know.

I will stand by the fact that I know I can get better sound out of USB than I can out of S/PDIF or HDMI from a PC.


So you are saying that despite the fact that both of these links are digital, there could be differences in audibility. If you are agreeing with this, I have accomplished a ton.

One then has to wonder why there would be a difference. We are both in violent agreement that the data samples are getting across all of those links reliably. So if it is not the data samples that makes the sound different, what could? Answer is what I gave in the first post: the timing.

So digital audio is not "digital" after all. It is not it works 100% of the time or not. It works all the time as far as us hearing something, but its fidelity can be different due to implementation. I call digital audio half digital for this reason.


"May very well" is a figure of speech, not reality. Reproducing 24-bits of precision is extremely difficult right now. Should I expect next week to be able to do that? This is not a computational problem which gets easier with time.

PLL technology we use for extraction of audio clock timing was invented in 1923. You would think ~90 years would have been enough relative to your comment but it sure is not enough given the measured numbers for HDMI.

Any more generalizations you want to put forth as facts and proofs?

Amrim, are you projecting your recent serious failures onto me? You've made a number of serious mistakes just today, including citing these obviously flawed results from this local studio guy. He blew audio testing rule number one which is "Thou shalt match levels".

I know better than to waste much time arguing with true believers who think only they know the truth.


The above shows how completely out-of-touch with reality you are, Amrim.

You don't get any points for finding me saying things that I have been saying for 30 years or more. You are way behind in your reading.


Not me.


When you are dealing with audio components whose complexity is on the order of an AVR or a surround processor, it is almost a surprise when things sound the same without a lot of care. When people are assembling complex systems, one kind of difference or the other will often be found. Some inherent in the equipment which is interesting, others due to random differences in setup and adjustment.

Besides, a goodly portion of every listening test is in the analog domain. Power amps, speakers, etc.



Of course digital audio is digital. But just because two complex links are digital doesn't mean that the polarities and levels automagically match. Frequency response differences can be intriduced in the digital domain quite easily these days.

Amrim we now know that you are less sophisticated than a beginner when it comes to doing listening tests. Just about everything if not exactly everything that you've mentioned of your own work were based on sighted evaluations or their equivalent in botched blind tests.

Whether you realize it or not, you did not give an accurate answer when you were asked if you knew who you were dealing with when you deal with me, or if you even knew what an ABX test is. You simply don't.

Sorry I didn't see it. The way you do the test is that you change states with your eyes closed but then decide to open them when you are done. You can stop one either outcome. I.e. the better one or not and then look at the display and see what it means.

Let me know if it is still not clear and I will explain more. It is no different than not looking at the label of two sodas, tasting them, and then turning the around to see which one was which when you are done.

I didn't actually. I said you were mistaken about your understanding of jitter in digital domain. I will go ahead and explain why now.


Sounds like you are trying to extrapolate your analog experience to digital. As an old analog guy, I like that you know something about that space. Sadly, you cannot confuse sampling jitter and speed variations in analog domain. They are two completely different things.

The type of jitter we are talking about is timing variations as in when the DAC is instructed to output its next sample. These tiny variations modulate the "phase of the clock." We are NOT talking about taking the pulse itself and slowing it down or speed it up. But rather, when the tick arrives and the DAC acts on it.

Here is a picture:



As you see the digital pulses simply dance back and forth in the presence of jitter. Their frequency (i.e. number per second) is not changing.

Turns out if we make some simplifying assumptions, we can compute what the jitter must be for us to achieve minimum noise floor of a 16-bit digital system:



We can prove the above by performing an FFT simulation of a 7 nanosecond jitter at 3 Khz acting on a 10 Khz signal:



You can see our distortion floor is now -80db as the math says, instead of -96 that is represented in an ideal 16-bit system (size of our audio samples in CD). The same 7 ns of jitter would bring our noise floor up to -73db if our input frequency is 20 Khz. That would not be all that good. If I pay to play 16 bits, I want to get 16 bits come hell or high water!

If I plug in your 1usec jitter number in the formula, my side skirts would shoot up to -30dbfs. Assuming the PLL can maintain a lock at that, you have one heck of a lo-fi system! [The formula is not very accurate for high levels of jitter like this – I am just playing along.]

It doesn't. As I explained, you are mixing apples and oranges. Just because two things sound the same, it doesn't mean they are. Maybe one of these days you will tell me what experience you have in digital audio as I asked on the first page .

You mean this page? http://en.wikipedia.org/wiki/Wow_and...er_measurement

"Wow and flutter measurement is carried out on audio tape machines, cassette recorders and players, and other analog recording and reproduction devices with rotary components (e.g. movie projectors, turntables (vinyl recording), etc.) This measurement quantifies the amount of 'frequency wobble' (caused by speed fluctuations) present in subjectively valid terms. Turntables tend to suffer mainly slow Wow. In digital systems, which are locked to crystal oscillators, wow and flutter are usually insignificant (variations in clock timing, referred to as jitter are a different issue, occurring over a much shorter timescale with different audible effect, and do not qualify as wow and flutter)."

You should not make this so easy for me .

So, what is the crux of your argument Amir? Are you claiming that phase modulation and frequency modulation are somehow fundamentally different?

Tell us more. How does frequency response differences occur in digital domain? In quiring minds want to know!

This will be rich.


The shoe fits. You demonstrate your lack of understanding and experience by asserting otherwise.


Except they aren't.


No different from analog recording media.


Here is where you show your lack of practical experience again. If you play back a sine wave from a source with wow and flutter the sine waves dance back and forth in an identical way.

Furthermore, the frequency is changing, and then changing back. If you have low frequency jitter you may be able to directly measure the change in frequeny.



If ever in your life you actually attached a FfT to the output of a phono preamp, with the turntable playing a suitable test recording that is probably what you would see, Since you assert otherwise, you show that you have never done your homework. I've done my homework, which is really quite simple and takes almost no special hardware or software to speak of.

You've got a $25,000 AP test set that would make all this clear but you lack the understanding and vision it takes to do your homework. Perhaps you should read up on how to use your AP test set to measure wow and flutter and look at the FFT analysis.

Put me to the test. Look at wow and flutter from an analog player. You will see familiar things because whether you call it wow and flutter or jitter, its all FM disortion. Some of the mecahnisms that cause FM distortion also stimulate some AM distortion, os things are never really pure.

You've never heard of digital filters, I take it. Google is your friend.

Let me intorudce you to my other identity, that of a live sound mixer/technican and also a live music recordist. I have a digital console with a 4 band full paramtric equalizer on every input (56) and output (At least 10) . Fun!

Another one of those ROTFLMAO moment.

Aren't you implying those 4 listeners heard an audible difference though? Without retesting those four, who know what they really heard, in those tests other than the results showed a significance. Perhaps it was a fluke?

I read an interesting statistics article some time back that mentioned that in pi, that 3.14 number the decimal digits are random, yet there are 2 sequences of 10 numbers that are either even or odd in the 1st 1000 digits of pi.
145 people in the test, probably statistically, I have no idea, you might expect some people to get statistically significant results by chance alone, no?