OF course, the amp's warranty just expired! I told my Bass buddy John ( fantastic player and great friend) I would post his amp issue here, for maybe some help? John has little ( but powerful) Mark Bass amp head, and pairs it up with a Mark Bass ( vertical ) 2X10" cab. ( I think 2 years with rig now) The last few weeks or so the amp is making an intermittent POPPING noise - like a HANDCLAP! Just comes and goes... The actual amp volume and sound do not seem to be affected when playing- no other weird noise or distortion- just this 'clap' that invades his amp. He is pissed! He thinks the amp needs to be played a while before this shows up. He took it to a local service tech; dont know what tests they do, but found nothing. We played last night- he used the same Mark Bass cab with his old GK head- no issues. Any ideas what might cause a 'slap-pop?' Thanks Mucho!