Well .... My affair with my Rumble 500 head has ended, this Sunday, we were doing a benefit/open mic, which was a bit long, 1-8 pm, out on an open stage, with good reliable house power, ( voltage was 121volts, I checked with my Flukie multi meter, and good ground ) after about 5 hours it just plain quit, wouldn't power up, air vents unobstructed, checked/swapped the power cords, brought out my back up amp and finished the gig, while packing/ tear-down, I tried it again, on another known circuit, same issue, won't power up, well this morning, it Powers up, but there is a one one thousand, two one thousand wait for it to power up, called Sweetwater, they had me go through a couple of ask and answeared questions, end result, is I got a RMA# and this amp is going back, just can't have an amp that may go out, granted any amp can go out, at a moment's notice, but an amp that's a couple of months old shouldn't do this, the back up amp was my other Rumble, Rumble 350, it really wasn't that hot, granted my definition of hot is somewhat different, as I'm in the Houston, Tx area ... Oh well, let's see what happens next