I hesitate to contribute to this thread because I'm not very technical. But as a guy who likes classical music, I may have one point to contribute.
A lot of recordings nowadays do not even pretend to convey the experience of a live concert. What's more, not even live concerts do - some of them at least. By the time you put $1 million worth of equipment between you and the audience, you might as well play them a record. (It's been known…)
Now every truly live experience takes place in a particular environment and provides a specific sound, and this is never uncoloured, flat or neutral. That's the way we experience music, sound plus space.
I think that may be why we can handle dacs and amplifiers that "colour" the sound. Okay, it doesn't reproduce exactly what's on the record, as the neutral sounding equipment does,but what it adds is no more than a variation on the sound–space picture, and we have a very high tolerance for variations.
Anyone who's been in a recording studio knows the shock when you first perform in one. There's neutral for you!
All of which might explain why I didn't care for the O-DAC . . .