For what it's worth - I just picked up a pair of HD600's also (seems lots of us got these at a good price recently, after rebate). I'm using my Nakamichi headphone jack with a dummy tape paused for recording. I can easily adjust level and have plenty of gain.
Would a separate headphone amp sound better - probably, but it's damn fine now. I would definitely have to audition one and hear the difference before plunking down the cash. I also did some research and it seems like most prefer tubed amps over solid state, even stating that the inexpensive tubes still beat the expensive solid state's. More euphonic probably.
Enjoy,
Bob
Would a separate headphone amp sound better - probably, but it's damn fine now. I would definitely have to audition one and hear the difference before plunking down the cash. I also did some research and it seems like most prefer tubed amps over solid state, even stating that the inexpensive tubes still beat the expensive solid state's. More euphonic probably.
Enjoy,
Bob