This document has been already mentioned in another thread: http://www.esstech.com/files/4514/4095/4306/Application_Note_Component_Selection_and_PCB_Layout.pdf, so it might worth posting here a bit of it:
It's clear that some opamps are measuring 2-3 dBs worse or better than others, in respect with THD and noise. Different measurements between opamps is a fact and it's also stated in every opamp's datasheet, but it's hard to say that few dBs in THD or in noise will actually make the audio chain to sound worse or better than another one.
One thing's for sure: pre-ringing and post-ringing is altering the sound, especially the first one, because it doesn't exists in the nature (there's only post-ringing), so if a DAC will pre-ring, then this might be felt as a different sound by some trained audiophiles (this will not appear in our standard THD & noise measurements). Let's wait a bit more, maybe some of us will be able to spot some differences between 2 devices in an A/B test, then will do some measurements and find some differences to post here.
One thing's for sure: pre-ringing and post-ringing is altering the sound, especially the first one, because it doesn't exists in the nature (there's only post-ringing), so if a DAC will pre-ring, then this might be felt as a different sound by some trained audiophiles (this will not appear in our standard THD & noise measurements). Let's wait a bit more, maybe some of us will be able to spot some differences between 2 devices in an A/B test, then will do some measurements and find some differences to post here.