Good evening from California, krub!
In general, more detail, wider/deeper soundstage And amazing separation of discrete instruments. Obviously, the source quality really needs to be good, but that’s the idea. I've heard things on my Bifrost 2 that I didn’t know were there on many albums, the latest being the new remaster of the Beatles’ Abbey Road. You also get true balanced and better power supplies and components as you go up the ladder. I have Modi Multibit and Bifrost 2, though I have heard all their DACs. As I don’t use a USB source very often, I strongly favour separate components. What is your budget? I hope this helps answer your question.
The Schiit site has links to reviews as well. Also, another forum here by Jason Stoddard, “Schiit Happened”, and Mike Moffat’s thread “What a long, strange trip it’s been” are great places (better than this thread) to ask this question. Glad I saw your post!
Note: Stoddard and Moffatt are Schiit’s founders, and Moffat is the digital guy who has designed all the DACs...