Ok, i've got a pretty goofy amp. I bought it used for a good price, but upon playing on it, i noticed something kind of weird. Occasionally, when i play my bass, a weird click will be heard. Sounds a lot like chalk being tapped on a blackboard. It only seems to happen when I touch a string; i don't have to play the string to hear the sound tho. It also goes away when I turn one of my two tone knobs down. However, the bass is crappy to begin with, and without both of the tone knobs all the way up, i get this boring, flat-ass sound. I'm not sure if it's just the amp, or a combo of the amp and one of my pick-ups, but it's annoying as hell. help?