I dont think I have done anything too special. I tweaked mpd.conf just a bit for the DragonFly.
edit: I also disable Airplay since thats not my use/purpose
My setup is:
RPi with DragonFly in one USB and a 7port USB powered hub with wifi and HD with all my music.
I have James Taylor, Otis Redding, Stevie Wonder all at 192. Stones at 176. All play just fine.
The funny thing is the other day I ripped an older Blues CD and was getting white noise as it changed through songs....go figure