just a shot in the dark, but I have sound isolating headphones and when I power the isolation option on, if my batteries are getting low, then I start to get nasty sounds and cut outs especially at the bottom or high ends, kick, crash or loud whacks on the snare or floor toms will do it.. if I play soft all is well for a while, until the batteries really go then it just dies.. does your set have an option for non-isolation and do you get the same result?