Pretty nice, a bit brighter than what I'm used to. Bit more energy in the upper ranges compared to the HA-160 and Mini-X. Punchy and tight bass, mids are pretty neutral (especially when compared to the Ember). Seems to have more than enough power to go well with anything I have (still haven't tried any IEM's with it).
HE-500 pairs up with it fairly well (really tightens the bass up) but I do prefer the LCD-2 with this amp.