The comparisons you make will be interesting. The fact that "DACs sound different from each other", even at what most would consider "high end" prices, does bring up a question. Why isn't there something like the RIAA curve for DACs? How can we ever know that a manufacturer is shooting for "neutrality" or not?
In other words, say the output from your DAC is from 0 to 2 volts (RCA jacks). How can we ever know that for any of the thousands of volume levels at thousands of frequencies from 20Hz to 20KHz, that a DAC outputs exactly the level it should based on the digital input signal?
Or is that at best a "pipe dream" and all DACs will always sound different, and some are accidentally or intentionally "voiced" to sound a certain way?
What is "truth"? And if we could get "truth", would we want it?
Six DAC Comparison
I am in the middle of comparing the sound of six different DACs in my system. I own them all (I know weird) but one of them is still within a trial/return timeframe.
Not to share specific comparisons today, but a couple of observations so far are that first, they all definitely sound different from each other. On one hand, they all sound pretty good and play what is fed to them without significant flaws but on the other hand there are definite sonic differences that make it easy to understand how a person might like the sound of some of them while not liking others.
Second, raises the observation that most of them must be doing something to shape the sound in the manner the designer intended since one of the DACs, a Benchmark DAC3 HGA, was described by John Atkinson of Stereophile as providing "state-of-the-art measured performance." In the review, JA closed the measurements section by writing, "All I can say is "Wow!" I have also owned the Tambaqui (not in my current comparison), which also measured well ("The Mola Mola Tambaqui offers state-of-the-digital-art measured performance." - JA). The Benchmark reminds me sonically of the Tambaqui, both of which are excellent sounding DACs.
My point is that if the Benchmark is providing "state-of-the-art measured performance," then one could reasonably presume that the other five DACs, which sound different from the Benchmark, do not share similar ’state-of-the-art" measurements and are doing something to subtly or not so subtly alter the sound. Whether a person likes what they hear is a different issue.