Not to hijack the post, but given Rrog's observation that we adjust to sound as tubes wear, how do you decide when to replace power tubes?
OK to replace one power tube for amp?
I have Joule Stargate Monos that use the Russian 6C33C-B power tube, two per amp. One of them isn't holding bias very well... wandering a bit. Can I just replace the one tube? Each power tube is individually biased in this amp and I've heard that matching pairs with 6C33s is just not something that happens so it would seem ok to buy 1 but I didn't know if having tubes of different ages was bad.