Like I said, you may need an amp for the HD600's, but not true in all cases. I built my portable amp for about $30, nice Cmoy/Hansen amp.
Overkill for computer use? In the computer world, NOTHING is overkill. Otherwise we wouldn't overclock, mod our cases, rob banks to buy the latest GeForce gfx card..........lolol
And if you've never played Q3A thru a set of HD600's, you're missing out.