Best headphone amp for new Senn 650's


I just ordered a pair of the 650's with an upgraded cable from Drew at Moon Audio. I have been over at head-fi.org and Headroom Corp. and looked through these forums too and have come up with several possibilities for a new headphone amp. My question is, is there something that would considerably improve upon the Antique Sound Labs MG Head (older version with transformer, and Telefunkens) that I currently use with my Senn 600's? I am tempted by the Headroom new Max, the Grace 901, the Sugden Headmaster, and various other esoteric things I read about at head-fi. There are a lot of headphone listeners here, too. Any thoughts on whether I could substantially improve on the MG Head? Maybe other tubes than the Telefunkens I now use?
sc53
Sarah- the folks over at head-fi are often younger and/or really into DIY and specs. There is a lot of discussion about rolling op-amps, and how something must sound better 'cause it it has bigger tubes and heat sinks and all. Some of the serious folks there have very good ears, but there is a lot of chaff to separate out. I have not heard Singlepower, or PPA. Gilmore amps are designed by Kevin Gilmore, who is an academic type who has released several headphone amps designs into the public domain, and some of them are being "manufactured" by folks you can find on Head-fi. Each one is typically different, tweaked with diff caps, or op-amps or whatever. I agree that the RKV looks awesome, but I'venever been able to hear one. One member owns a Moth SI-2A2 and says Moth will customize those for your particular cans. He has also heard a prototype of a new amp the owner of Moth will be selling under another company name later this month for about $400, which he says is quite remarkable. I have heard one of the Emmeline amps and it was quite good but not remarkable. Email me and I'll give you the name of the guy to get more info on the new moth amp, which he auditioned with 650s, I belive.
I bought a pair of HD 600's with my Benchmark DAC-1 and am very happy with it. The benefits obviously being that for the 850.00 you get a very high quality DAC.

Rob
I am forced to chime in with my opinion on the Earmax Pro. I had a Headroom Max (SS amp) and the Earmax Pro is simply superior with HD650s--more liquid sound, less fatigue (crossfeed notwithstanding), amazing bass.

Be aware that the Earmax PRO is NOT the same as the Earmax--the Pro version can drive some of the more difficult headphones that the standard Earmax cannot drive effectively.
The big picture in the centre of this site:

http://ipodstudio.com/index.php

shows a Larocco amplifier which was designed to use with HD 650s. It's off PPA design.

Click on the picture for more pics and details.
Ive used my rkv with my hd600s for four years now, sounds fantastic but I cant compare to anything else as I havent heard any other amps. Ive never felt on the other hand that anything was wrong so never thought about upgrading. Its worked wihout fault for four years but I think I should look for some new tubes for a possible upgrade.