I switched back to the stock Russians (I think?) 6N1P's. They have a warm, fatter sound. Goes better with my vinyl. The 3 JAN 6922's are NOS I believe from looking at the boxes. They're nice too and have more of a transparent, detailed sound. Better match for the HD650's.
I get a feeling the tubes in the preamp has more of a overall effect on the sound than the tubes in the amp itself. If I'd guess I'd say 60% preamp 40% amp, from what I'm hearing anyway. What tubes are you guys using on your CSP2? I'm thinking about picking up some more varieties.
The driver tube will give you the biggest change in sound the little one in the front. I love the Genelex reissues.