What I think all your DAC tests fail to take into account is the great variation in SQ between the I-V and analog output stages of various DACs. If you think a quick and cheap op-amp will sound as good as say a discrete output stage in an Ayre or Berkeley DAC, well then...
I recognize and accept that many here at ASR believe that your distortion and jitter measurements tell the entire story audio quality. Even setting aside high-end audio manufacturers, I don't think that pro-sound/studio equipment firms would agree.
But anyway, have a great weekend all. We are getting our first low-elevation snow of the year here in the Sierra Foothills. Quite lovely!
Good point. Leaving aside the op-amp comment (my answer would be "it depends"), I agree that the output buffer and filter stages are likely a significant part of the output, but disagree the tests don't account for them. Amir measures at the analog output so they are most certainly accounted for in his tests. What we do not know, and have no way of telling without ripping the boxes apart and running more tests, is how much noise and distortion comes from the output buffers etc. vs. how much is from the DAC itself. For consumers, it's a don't-care, because as consumers we are buying a DAC-in-box and cannot isolate them anyway. How well they perform also depends upon the load, natch, but the line output load is pretty consistent for most audio components. And I've said a number of times that I suspect those analog output stages are what differentiate a lot of DACs, how they respond to glitches and HF noise, etc.
What might be interesting is to set up a few nominal test loads and see if there is any difference in measured performance, e.g. maybe 10k and 100k R's with a couple of different shunt C's (inductance is probably not a big player). Additional IMD and multitone testing would also be neat, but I assume Amir has to sleep sometime. Maybe we need to get the King more coffee?
I think a review of threads would show most of us don't think jitter and distortion are the whole story, but they are a big part of it, and provide a basis for comparison. Why buy a DAC that measures significantly worse on the bench? The bench environment is usually cleaner/better than the real world, so...
Snow, eh, we've had some, and could use more, but I'd be glad to hand you the sub-zero nights and highs in the teens and twenties we've had lately. At least I can broom off a few inches when it's that cold instead of breaking my back shoveling.