Oh yeah, +20db gain gives it a much warmer sound in the mids. Now Marley sounds like Marley. The bass is a bit more integrated into the picture on high gain as well. It's weird how low gain seems to give slightly smoother highs, but the mids are recessed with the vocals sounding very distant. It's easy to listen to, but kind of dead compared to high gain.
Going back to some classical. Extra gain makes the sound stronger, slightly less delicate, but warmer and more engaging. Will have to try this for a while. Hard to concentrate, now I can't work anymore.... $#*%!!!
The soundstage gets wider on high gain as well... Cool. Thanks! (Btw, did you like the HD600 or 650 better with this amp?)