Hey there,
I was recently given a Peavey Classic 30 by a family member. When operating the amp itself, there's no problems aside from what seems to be some vibration when played through, which I believe to be the tube guard, as it only occurs at high volume.
However, whenever it is turned off (as it is an older model, there is no standby switch) the amp emits a loud scratchy pop. A google search suggested it was something to do with the pre-amp and to turn the pre-amp fully down before switching it off, but this didn't make any difference.

What could this be? Could the amp itself be damaged as a result of the pop?
Quote by AeonOptic
What could this be?
It's what turning down power switches do if the master volume's not all the way down.
Quote by AeonOptic
Could the amp itself be damaged as a result of the pop?
Name's Luca.

Quote by OliOsbourne
I don't know anything about this topic, but I just clicked on this thread because of your username :O
Quote by Cajundaddy
Clue: amplifiers amplify so don't turn it on if you need quiet.
Quote by chrismendiola
I guess spambots are now capable of reading minds.
Thank you. I checked out my amp, and since I don't have a master volume I turned off anything that might affect the volume when it's being turned off. It turned out that my boost switch was the culprit, and when switched off the popping sound went away.