Need help with Grado 325i vs. Senn 600's


I am looking to get a good pair of cans since I am in college and cant afford the speakers I want. My buddy just got the 325s and they seem nice, but I hear a lot about comfort. How does sounds compare? I will be using cans alot, so comfort is an issue. What about an amp? Someone hit me with some knowledge.
voodoochild
Do the Sennheisers NEED an amp? Is 200 hours on a headphone a lot when looking to buy pre-listened? I listen to a lot of rock, reggae, downtempo, and jazz, which headphone favors those listening styles?
Voodoo- Neither of those phones will give you anything like what they are capable of w/o a headphone amp, but you can use one in place of a pre-amp in most systems, if they have a loop out feature. For detailed reviews, go to head-fi.org. Most folks feel that the Grados are more forward, the Senns more neutral. The Senns are definately more comfortable to me. 200 hrs is not a lot of time if you are buying used.
I've listened to both and to me the Sennheisers were too laid back. Especially for rock. They just didn't have the slam of the Grados.

On the other hand, I don't think you'd find anything more comfortable than the 600's.

Both will benefit from an amp. If you're going to try to run without an amp, get the 325i's.