Sorry if this is the wrong place for this thread. I have a DSL50 amp that I've been using for about 1 year now without issues. A few nights ago I started getting some insane feedback from the amp. It was near the end of the night so I shrugged it off. Unfortunately a few nights later when I plugged in the feedback returned immediately. I used to have to fight to get feedback, but now it comes in as soon as I run some distortion, either the onboard version or through my effects pedal. I've run several guitars straight into the amp and I get the same result, unbearable screeching. Could it be the electonics inside the amp? Tubes? Any help is much appreciated. This was an expensive head so I would hate to have to sell it and get something cheaper. TIA. adrian.