Hello all: I have a Peavey XR500C mixer/amp that just started acting up and it is getting worse. The symptoms: If the amp is working fine, at some point during a performance it kicks out. If I turn the volume all the way up, you can here scratchy sound at a very low level. The only way to get the sound back is if you turn the main up almost all the way and send any loud signal through it (guitar, vocal, whatever). At some point (30 sec - 1 min), the sound kicks back in (threatening to blow the speakers of course. It will perform fine until it kicks out at some other point. It is not blowing the fuse, but I can only guess there is some form of thermal overload is occuring. The weird part is that if I turn off the amp and allow it to cool down, the problem is still there when I throw the power back on. I then have to "force" the amp to output again by turning the main all the way up again. If this was a thermal problem, wouldn't the problem reset itself after the amp was turned off and cooled. It almost sounds like an electronics problem (solid state system). But the mixer is still outputting to my monitor rig as well as other output connections, so the electronics still appear to function, yet no output to the speakers. Now for some variables I have introduced to the amp recently. I just bought a small monitor system as well as upgraded the speakers from 8 ohm to 6 ohm. The speakers have been in place for months without the problem coming up and the problem came up BEFORE I bought the monitor system. Maybe something with the speaker impedance? It's a small mixer/amp and I'm thinking about replacing it. But, it has been a work horse and packs a surprising punch. I'd like to save it if not for posterity and to boost moniroing capability. Can anyone help? I'm a newbie at the elctronics piece, so have some patience with me.