The 580/600/650 will be to hard for your computer to drive without an amp. I would recommend you check out anything the the Grado line starting from the SR-60's and up. The higher up the line you go the better they get.
I have the SR-225's and like thm very much. They are easy enought to drive that my ipod can handle them. You can also ge the grado 1/4 to 1/8 adapter its a few buck more than other adapter but I like the design (does not put added pressure on the 1/8 headphone plug) and is well built.
My Grado headphone take an enormous amout of time to break in. At least 300 hours but once they do they are worht it. My advice though is to stay away from the SR-325's, so say that they a little fatiging afterawhile.
You can read more about them at headroom.com
I have the SR-225's and like thm very much. They are easy enought to drive that my ipod can handle them. You can also ge the grado 1/4 to 1/8 adapter its a few buck more than other adapter but I like the design (does not put added pressure on the 1/8 headphone plug) and is well built.
My Grado headphone take an enormous amout of time to break in. At least 300 hours but once they do they are worht it. My advice though is to stay away from the SR-325's, so say that they a little fatiging afterawhile.
You can read more about them at headroom.com