Not the same problem as yours, mine is a crackling master volume pot. Been there from new, I think it's a fairly common issue with these amps. Most of the time it's not too bad but on occassions it really can make me, band mates and audience jump.
Enjoy the trip and just walk straight to the counter without looking at the displays, if you ignore my advice it could be a very costly trip. Absolutely don't look at the Overwater Jazz