Using mine for about a week now, couldn't be happier. Fast, lightweight, and great SQ, beat down my iPod Touch (that got stolen) out of the water.
I'm using a pair of cheap Phillips IEM as a portable rig, and it still sound very nice. Bass is there, mids are good, the highs are kinda harsh. At home, it drives my Grado SR60i pretty good, with even i higher volume than my onboard soundboard is able to.
I still need to learn how to use all the EQ and crossfeed options in my advantage, tho.