Headphone amp for Sennheiser HD 600/650?


What are the most synergistic headphone amps for use with either the HD 600 or 650?
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No doubt the Woo's are wonderful, but at a price, of course. I've found great synergy with my HD600's in a Peter Millet Mini-Max, which (if you are into DIY) can be built as a kit for about $260. Or purchased used or from various builders over at head-fi.net
Heed makes a superb head amp for the price. Uses discrete dual mono output and a large toroidal power supply, not a wal wart power supply. I bought mine for $500 and it will drive your Sennheisers with authority.
Thanks for the responses. Woo is on my short list. I owned the Heed for a while but have since sold it. I agree that it has plenty of authority and power, but ultimately dry.

I also have a Bryston BHA-1 on my short list because of its flexibility and feature set. I've not heard it though, and my past experience with Bryston (Original 4b, .5b and later a BP 25 also left me feeling it was a little dry- maybe Bryston gotten better since I last owned a piece of Bryston gear- maybe 13-14 years ago).

Never heard of the Millet, and DYI is right up my alley- I will check it out
Ptmconsulting wrote,

"No doubt the Woo's are wonderful, but at a price, of course. I've found great synergy with my HD600's in a Peter Millet Mini-Max, which (if you are into DIY) can be built as a kit for about $260."

Well, yeah, but...

I see that a Hybrid Millet Mini-Max goes for about the same cost as a WA6. (Am not into the whole DIY thing).
Well, its been a while. I wound up buying and building a Bottlehead Crack and then added some bypass capacitors and NOS tubes. Sonic bliss-