I’m selling my GK MB500. Please read below. WARNING I’m selling at a low price because it has an issue that I don’t feel like dealing with. The amp would work perfectly and out of nowhere the volume would drop and/or it was start to distort. Once this happens, a slight tap on the head brings it back to normal. There is no indication on when it would malfunction. Sometimes it would go months and not malfunction at all. I believe it has to do with me transporting it and shaking it a little. I emailed GK and they said it sounds like a loose wire or solder. They told me to ship it to them or drop it off at an authorized GK repair center. There was no mention of how much the repair would cost. The head is out of warranty. I have a new head so I don’t feel like getting this one fixed. Prices is $200 shipped CONUS. NO TRADES!