I've recently purchased a Peavey 6505+ for an incredible price, and i've just wanted to learn more about tube amps. i've used the search bar but i haven't found a thread about just tube amps and what not. Is there a website that is specific about the different power tubes, pre amp tubes, how to bias, etc...? a link>

I know im going to have to change the tubes at some point, so im just trying to get a head start to what replacement would best suit me.

Also how much would Guitar center or Samash charge to replace and rebias?Thanks in advance