Most ambient IMO (Biosphere, Bass Communion, Thomas Koner, Namlook, Bill Laswell, Stars of The Lid for instance).
Certain kinds of Jazz likewise, Jan Gabarek for instance. Pop rock, such as Talk Talks Spirit of Eden does great I think. Detroit stuff like Drexciya also shines in all its raw harshness with the K701.
I know this thread has been dead for a whole year, but I'll post just incase anyone checks it later. Has anyone tried listening to R.E.M or the Who on their K70X's. I know I should probably be looking more into Grados for the type of music i listen to but im drawn to the K702s like a moth to a very expensive, and hard to drive flame