first time with a bass knob. i have volume all the way down while doing something else. went to the amp, turned down the gain, unplugged the bass knob. sub went nuts and amp went into protect. now stuck in protect. i disconnected everything and re-installed the amp. still in protect. it is a sundown saz 2500.1. worth keeping if i know where to look in the amp. never messed with the internals before.