Another source of great advice and service is Jim McShane. His site isn't particularly easy to navigate but just email him with your question.
Sunfire vacuum tube control center tube upgrade
I'm thinking of upgrading the stock tubes in my Bob Carver Sunfire vacuum tube control center preamp. There's 3 stock tubes 6DJ8 or 6922. The manual suggests 6922's, saying they have less noise and microphonics than 6DJ8's. Any suggestions on tube upgrades or feedback on results anyone has experienced?