Hey, everyone -- what should I get as a backup amp?

[Spaced Out Ace]

It's always good to have a few spare tubes around anyway, so no harm there.
But if the problem is something else, yeah that's lame.

What are the issues you're having?

A sort of popping or "ppffffp" type noise through the speakers. I'm not 100% (it's a bit difficult to see) but I'm thinking the left tube (from the back of the power amp) is possibly going red.

If it was bought new, then shoot fryette an email asking for advoce. They might sort you out.
Tubes do shit the bed at their own pace though. I've had ones with countless hours on them and then a fresh set will have one pop in the first 50 hours. This is why the most fool proof backup is something solid state!

Interesting. I've not had fresh tubes Chernobyl themselves in such a short time, so I guess I've been lucky.

I did have 6 speakers in a Randall Lynchbox 412 go weird on me, and the best I could ascertain is that maybe it was the Seymour Duncan Powerstage 170. Otherwise, I'm not sure what the deal was.

[Guitarbilly]

Definitely sounds like a tube issue. But it could be just the 12AX7. If you have a spare, try replacing that first.
.