Have tried this, has clean sound with a bit emphasis in treble, detail and airiness are always there.
but for some songs I feel the treble "attack" can be a bit too hot and the vocal presentasion can little lack of body.
I think paired with some warmish cans will make good result.
I think as DAC+Amp combo, audinst have better balance presentation, while U100 more toward to brighter (not so bright till the difference like night and day, but it's just adding treble presence from Audinst) yet more fun sounding, it's so good for rock, the guitar energy will be easier to feel than on Audinst.
I don't know about burn-in, because I heard them only at meet.
Edited by TheMiddleSky - 5/2/11 at 7:35am