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a) it's not an appeal to authority. These are genuinely interesting considerations, and food for thought b) I'd be happy to quote any other engineer offering a semblance of explanation for some of the aspects of digital audio that practically every audiophile experiences daily (whether they know it or not) c) I'll agree that AS is most probably the wrong place to discuss the inner workings of audio. Most people here don't care. The resident experts are more interested in promoting their products than getting involved in these discussions d) your point of view is completely irrelevant to me. Feel free to block my account if you wish. AudiophileStyle no longer offers much content of interest to me. 99% of the posts are written by the same 1% of contributors, and frankly most of them have little value.

Listening to delta files recorded with an ADC is not an "objective" way of evaluating DAC accuracy. Period. There is no need to provide "objective" data to understand that something makes no sense... If you don't see the value of providing expert's information on audio "mechanisms" in this forum, fine. I was curious to see what another "expert" thought about it, but his comments on those technical aspects were off topic, and the discussion on the deltawave tool is secondary. Goodnight.

I am just reacting to his claims. I am pointing out what I see are the limitations of this tool - I am sure it has some use cases, but vis à vis my original post it cannot be used to confirm/infirm these hypotheses.

So what are you saying exactly?

So we cannot provide technical data in the objective-FI section? And if we do, we cannot discuss it? Nonsense...

No, you cannot reach any conclusions on DAC accuracy.

Even worse! You listen to noise (or it's absence). What does that tell you? Nothing really. And anyway you are back to listening to a system. As I said, this is certainly fun but I don't see how you can come to any serious conclusions regarding DAC accuracy.

The original file can only be listened to through a system... Let's say you play a music file through a DAC and record it using an ADC. Then you listen to the resulting file, and compare it by listening to the original music file. You are listening through a system, and cannot make any assumptions on any subjective differences (or the lack thereof). It's probably a fun tool to play with, but I don't see what conclusions you can come to in terms of DAC performance and subjective results. Especially not the ones you made above (no jitter issue with USB, or no jitter issue with an on-board clock).

I meant when you listen...

OK, but what does it tell you? How do you account for differences with the original WAV files - is it the DAC or the ADC that are generating differences ? How do you interpret the significance of differences in terms of SQ? If you listen to the results, it's even worse because then you are back to simply comparing DACs / systems without knowing how accurate any of them are. There is no '"reference" against which you can evaluate results.

Have you used this to compare an original WAV file with it's recorded playback from a DAC (using ADC) ? If so, what does it tell you?

Jitter tests, AP analyzers work with test signals, so no chance of measuring anything significant. For the limits of USB, read over the post I linked.

I'd be curious to know more of what you are doing.

Not really. It's pretty clear from his explanations and measurements that clock performance can be degraded even with an on-board clock. USB does not change anything in that respect.

Its been discussed over and over again. Here is a pretty good recap from our friends at ECD, explaining what they think are at play: https://www.diyaudio.com/community/threads/is-jitter-an-issue-with-usb-signals.290973/post-4722474 and https://www.diyaudio.com/community/threads/is-jitter-an-issue-with-usb-signals.290973/post-4724351 Quoting a passage on "measurements" (in the context of jitter): "Graphs won’t tell you what audible advantages or disadvantages to expect, because these jitter graphs are based on single or dual test tones (fundamentals). Music is infinitely more complex, it has a fast changing dynamic spectrum that creates the biggest problems in any DAC. The jitter graph won’t cover this because it only shows the DAC jitter response with these test signals only, it doesn’t show what happens when the data content and spectrum are infinitely more complex." Proper measurements would require comparing a DAC's input and output (after conversion back to digital), using something else than a single test tone. Good luck with that !