I just posted this in another thread, but it totally applies to this thread too, so I'm reposting it here:
All this stuff about needing expensive amps is just a lot of misinformed opinion. There are plenty of pro audio monitor/headphone controllers/distributors/amps that cost very little but sound perfectly fine--no noise, no distortion, no coloration, and plenty of juice.
Seriously, just get something under $100 like the Samson C-Control or Behringer MiniMon or MiniAmp, and enjoy the headphone. There's no need for expensive boutique headphone amps. I bet most people probably can't even tell the expensive amps apart from the cheap pro audio units I mentioned, and even if they could, in a double blind test, they probably can't even tell which is which.
I can't stress how much I think expensive amps are a huge waste of money.
Oh, and another vote for the LCD-2. I like it even more than my $3,000+ Stax 007mk2/717 rig, and I'm just using the el cheapo Behringer MiniAMP and Samson C-Control with it.