So I had band practise today, and I left my pre-amp at practise (Mesa/boogie Studio Pre) So when I turned it on I got a loud LOUD feedback and popping sound. This was when standby was on (i.e shouldnt be anysound what so ever) But when I turn standby off its perfectly normal.

I dont have any clue what could be wrong. Any help?
maybe you blew a preamp tube..... it might be fracturing your sound from lack of power. lol if you have 60 bucks....