As many already know, I'm in the vintage and used guitar world and have known a few guitar players to literally try 50+ different tubes in the V1 socket (1st Gain Stage) to get their "tone"! The irony is that a good guitarist's tone is in their hands and will sound like themselves no matter what tube is here or there. A good example is Eric Johnson who is uber fussy but no matter what amp he is plugged into will sound like Eric Johnson.
However, home audio is different, many do look for the best sounding tubes for their gear. I'm in that camp, but I also agree that once you put some tubes in that sound wonderful, hands off.
I did have a quad of Ampex 7308's that sounded wonderful in my old Marantz's, but I used a quad of Mil Spec 6922's that got the bulk of the playing time. I switched only when I wanted a different feel for a while.
Jim
