I can recommend the NJC Audio Monitor II headphone amp. It doesn't get a lot of mention although it has been reviewed on this site. It's neutral and revealing with plenty of energy and punch. Some talk about it is on this thread...

http://www.avforums.com/forums/headp...mp-review.html

The only issue you might get is loud recordings if you are using an early gator board, which seems to go away at about -3db. This might not be an issue on mk2 boards. I suspect this will put you off though.

Sound character wise I'd say it blends the tidy, neutral, clean nature of the LM4562 and the open, fast, detailed, spacious nature of the AD826 you get when using the beresford's headamp, with the extra weight and drive you'd expect from a ballsy amp.