I have my problems with the "Computer Audiophile" and his site, but he has reported on his blind ABX comparison of the three new flavors of Schiit Yggdrasil DACs, claiming that he heard distinct differences among them even though they all measure very well (SINAD above 110 dB). Do you doubt him? What biases could lead to problems with such blind ABX tests and lead to false positives when it comes to ability to distinguish among them? As I understand it, he rigorously equated output levels.
Also see
https://goldensound.audio/2021/09/21/schiit-yggdrasil-more-is-less-measurements/ for some interesting measurements at different input frequencies for the Yggdrasil More-Is-Less. A single-frequency SINAD value may be misleading when discussing "sound signature differences" among DACs, for example. Bottom line is that measurements can fully describe the audio output of components; I'm less certain that we are entirely sure how to comprehensively interpret those measurements, nor indeed that we're necessarily measuring everything that can affect that output sound.
But I acknowledge that I'm quite ignorant on the science of this stuff. Just pondering some things here.
SINAD is only happens to be a useful metric for line level devices because it's generally line level devices which approach a degree of perfection such that their performance can be summarized with a single number. Power amps are sufficiently nonlinear that the single number isn't that descriptive; ASR provides a SINAD at something like 1khz/5 watts but it doesn't tell the whole story.
It turns out that it is very easy to make a transparent DAC, as evidenced by the fact that of the hundreds that amirm has measured for his own perverse reasons, the vast majority have noise and distortion below 80db of the fundamental tone. 80db is a very very bad performing DAC: it's easy nowadays to find one which is many times better. Remember that 6db is about half as loud, so 86 is twice as good, 92 is four times as good, 98 is eight times better, 102 is sixteen times better and so on. However, -80db is also an incredibly quiet signal. -80db is the equivalent of talking to someone one meter away, and then them walking 5 or 6 miles away. You can't talk to someone 6 miles away.
When someone says they can hear differences between 110db SINAD devices they are saying they can hear someone speaking or not speaking who is over 150 miles away. I think it is reasonable to assume that they are either mistaken, their test is flawed or there is something seriously wrong with our measurements, which go down to something like 130db with noise averaging.
So basically we are talking about devices which all do an essentially perfect job, which have slight variations in HF distortion caused by having a variety of filters.
I don't know about every test people have done on the audibility of cutting edge digital audio phenomena. I am not a scientist. However, I do have enough intuition about the db scale to have a sense of proportion about these devices.
The issue of the audibility of HF filters hinges on how HF distortion is weighted in the SINAD calculation. Perhaps someone can weigh in on that. Slow filters increase distortion at the top of the musical bandwidth, but let's say for example the HF distortion was incredibly bad- -60 db for example. -60db is incredibly damn quiet. I've done tests to demonstrate this. The idea that correlated distortion which 'blends in' with the signal would be audible at -60db is just not believable to me.
We all want the best, but DACs are something not worth worrying about. There is a lot for consumers and enthusiasts to learn about as they educate themselves about audio and I am a big fan of that. ASR has done an outstanding job educating people about headphone and speaker performance; both incredibly subtle and important areas.