Gk with hartke xl cabs I was using a wrong setup: intrument cable to the speakers I did not know tha was wrong, once the amp made a paff sound and stop working. At that moment was not important. Now I am using speakers cable but perhaps I damaged the amp before. The amp sounds good but when I boost the treble of the musicman (with the treble of the GK flat), it makes pffff" or "hiss sound Does a gk make a hiss or paff sound when you boost the high frequencies?? A hartke head trough a hartke xl cab I play yesterday at a practice room, does not make that hiss or pff sound when I boost the treble of the musicman. Perhaps the hartke has a filter. I need the opinion of hartke and gallien krueger users! Thanks!!