I'm taking a close look at the Ember. Would you recommend it over pretty much any solid state amp? (For use with the HD700, of course.)
Also, have you found a particular vacuum tube that you like best with the HD700?
At the under $500 range the Ember is hard to beat but if you can get the HA-501 it is a slightly cleaner sounding amp IMO. I only got to try the HA-501 for a few days last month and it was used with a few high end DACs so they may have had a impact on the sound also but being all SS if would come out cheaper in the long run. I still like the idea of being able to have fun with different tubes so I'll stay with the Ember for now.
As for tubes, most on the tube rolling thread for the Ember like 6SN7 types but I still like my Telefunken 12AU7, and new issue Mullard, Gold Lion and Tung Sol, much cheaper and easy to find.