From what I've read, they are far better than the HD595. (Never heard the 595).
They sound decent without an amp, but they really do deserve one and sound vastly better with one.
(Same situation as the HD650)
You could easily get away with using your Xonar DX for a few months while you gather your research and resources for an amp.
EDIT: oh, and about the bass.
I find that the HD580's have the perfect amount of bass. Not too much, not too little.
On the other hand, now that I think about it, they might be bit to veiled in the higher end for trance/electronica.
You may want to look into Denon D2000's or DT880's for electronica/trance.
HD580's are more for -great- dynamics, which is less important for synth music (in my opinion).
Edited by nullstring - 8/10/10 at 9:09pm