After buying a couple of expensive headphone amps, to my ears, they did not sound better than headphone outs of my Onkyo (at that time) or Denon receivers. I do suspect that some headphone amps color the sound on purpose though. The headphone amps I purchased was a Corda Headamp $240 and the other one I can't recall the name at the moment, but was in reality a preamp of some sort. The sites that sell pro audio gear have reasonable priced headphone amps if one is so inclined and that is where I would go now.
Nick
