I had a weird thing happen last night at a gig. First of all, I was using a questionable cab that was part of the back line. About 45 minutes into playing the soundguy told me he was getting a buzz from my DI out from my GK MB800. So I shook the cable a little and made sure it was seated well and the amp powered off. So reseated the power cable to make sure it wasn't loose and the power came back on, same buzz. So the soundguy started to run a 1/4" inch from my line out to a direct box and once he plugged one end into the line out and touched the other end, it shocked him. So we unplugged the cable. I then laid my arm across my strings and they shocked me. At that point I unplugged everything and had to run the rest of the night with no amp, just through DI. Has anyone heard of this before? I couldn't figure out if it was an amp issue or a cab issue or what. Any info greatly appreciated.