I put in a pair of 1965 Amperex white label USA 7308s, one newly acquired, into the Zen Signature Monoblocks. I'm trying to give tubes I've bought at least a couple hours in the gear to make sure they work. I've bought far too many as spares without doing this. I'm also putting them in white boxes and writing info on the boxes. As time goes by I forget the info on the tubes and the info once on ebay disappears. It's helpful to have all the info and test data for the future.
PS...one thing, among many, I like about these monoblocks is that matched pairs are not required as in the Torii. It allows me a lot of flexibility when buying. When recording data on boxes, I found one 7308 is not really a 7308 despite the tube being labeled in white print as a Government Contract Amperex 7308. The etched code revealed it is actually a 1965 Amperex 6922. I ran it for a long time in the past with another 7308 purchased from the same seller and was none the wiser...so I guess with the Monoblocks I can get away with running different tube types as well.
Anyway, this is a CD of Sessions Benny Carter did with Oscar Peterson...