I've noticed that my amp has become much quieter recently. It's generally a really loud amp and I've rarely needed to push it past '2' at rehearsals, even with a heavy handed drummer, but I've had to gradually turn it up more over the past few weeks even though I'm in a pretty quiet band and a fairly dead room. It might not sound like much but I was on 4-5 at last rehearsal, which would be uncomfortably loud before.
The only thing which has changed recently is that we have our own rehearsal room which gets pretty cold, whereas I used to bring my gear home every night. I always let it warm up for 20 minutes or so before using it but I wonder whether the cold has had a detrimental effect on it.
My initial guess is that the output valves (EL84) need replacing but I wondered whether you guys can offer some input.
If it is likely the valves (tooobs

) do you have any opinions on cryo ones? I think they're just regular JJ's in there but I've seen cryo ones advertised and wondered whether they're worth the extra cash?