Genre = orchestral, rock, metal, piano, synthpop, male vocals, female vocals, chiptunes, acoustic guitar, 80's dancepop, lots more...I always test with a good mix of tracks.
I've tried it with my Brainwavz B2, AD2000x, Grado SR-80, Futuresonics Atrio and TDK BA200. In every case, adding the Zo to the lineout improved the experience greatly. I have tried it with the HD800 and a converter, but the sound wasn't anything special. Mad Dogs need a lot of power, so not even worth trying them with anything less than a desktop amp, IMO.