Which Headphone Amp for Sennheiser 600?


I want to buy a used headphone amp to drive the 600, any suggestions?
bigboy
Now I use the headphone output of my SF Line 2, but for 2-3 years I used a Headroom Supreme which sounds great. A big advantage of the Supreme is that it is small and built for travel, ie you can get an outboard 4 "C" cell battery box for longer play time, an AC adaptor, and it also has a built in AA battery chamber. Other travel oriented accessories are available.

And it can be plugged into a pre-amp via the tape output terminal either with or without a "splitter". I've used the Supreme with both Senn, 580 and 600s. Cheers. Craig
Finally found an RCA-plug/phono-jack adaptor cable at the Shack ($4) that enables me to run my new HD600s directly off my Aleph P. Sounds great!
Thanks Rmml. It is easy to open up. I just didn't know which tubes to upgrade to. Thank you.