I like to listen mostly to Metal (thrash, death, progressive and so on) with some classical and blues sometimes. The phones I have are a Ultrasone HFI-780 and I have on my way a Grado SR225i.
At home, I listen to the music mostly in the computer (Macbook from 2007), which I have connected an external sound card (Line 6 UX1). I bought that soundcard because Line 6 is quite popular for guitarist, and it is a good gadget for recording myself or use guitar amps simulators on the computer. However, I don't know if it is enough for power my headphones.
The specifications of the soundcard doesn't help very much: http://line6.com/podstudioux1/specifications.html
What do you think?