mattcastore wrote:maybe a new power tube is worth a shot. should i be looking specifically to get a NOS Fender tube? or what other NOS brands might do well?
and in terms of recordings with the kind of guitar sound i'm looking for - if anyone is familiar with the Marked Men albums "Fix My Brain" and "Ghosts", that's kind of what i have in mind.
There's no such thing as a "Fender" tube. Fender never made tubes. Over the years, they did apply their label to tubes of other manufacturers, right up until the present day. They do own Groove Tubes now, but Groove Tubes never made tubes, either. They re-label imported tubes.
I would look for a 6V6 tube by RCA first. RCA tubes were some of what Fender used in the 1950s and 1960s. They're very good tubes. Ones with the black plate structure are more sought after. Gray plates are from the 70s and are also fine.
Other good 6V6 are by Marconi, Bendix, Mazda, Westinghouse, Tung Sol.
Totally acceptable and less expensive are by Sylvania, Philips, GE.
If you wanted to go new production, the JJ 6V6 is less shitty than the other modern 6V6s, and less shitty than all other JJ tubes which, in my opinion, are pretty shitty-- message board hype notwithstanding.
If you really want to try and make your Champ work, try a different 6V6 and a different speaker. I like Weber "Vintage Series" speakers a lot, though they're not super-cheap and you have to make sure one will fit in a Champ. The "signature series" are OK but not great in the 8" sizes.
Too much more tweaking than that, and you start to make it into a different amp. Of course it goes without saying that you should start any experiments with an amp that's definitely in good repair.