Hey guys, I have come across a issue with my amp that has occurred lately.

I have been playing it and it seems quieter than it should be when it's cranked up, so guessing that's the tubes.

However I find that if the amp is being played its makes a weird squeak noise. But I can replicate the sound when I hit it from the top (just to see it doing it). Is it something wrong or just a tube issue?
Running through:

Engl Fireball
Engl Slanted Cab
Ibanez Xiphos
Schecter C-1 FR Black
Ibanez GRG (on its way)

Boss Noise Gate, Zakk Wylde Overdrive, Boss Tuner, Zakk Wylde Wah.
Yep.. Just had my other guitarists fireball 60 do the same thing. It was the PI tube on his.
or the v1
tone slut

Mesa Boogie Mini Rectifier
jet City 2112 Combo
Gibson SG Standard
Gibson Les Paul Studio
Fender Classic Vibe Telecaster