Headphone amp for Sennheiser HD 600/650?

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-

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