Well crap, I was considering building another Crack in solid Cherry with shiny copper, but you have to use an adapter. It will handle the 6sn7, and most anything else you throw at it. I will figure out something, I hate for you to risk the only headphone amp you own. Maybe I can find a nice Microzotyl cheap and send that along with the pipe bombs, er tubes.
OMG a guy I buy tubes from all the time lists a Marconi tube, it was GE after all, now I need to buy a Canadian Marconi tube if I want the real deal. I will call the guy up tomorrow, he even knew what I was doing and I had already purchased several GE from him lol.
Luckily a lot of what I buy is tax deductible, I may win the steak dinner battle and lose the war otherwise.