I'm an idiot. In the original post I said it clicked at the same rate regardless of engine rpm..........the clicking does change according to engine rpm. The higher the rpm, the faster the clicking is.
I took the sub out of the tube and disconnected it, and there was no noise. I put it all back together and tried unhooking just the gain control and it still clicked at me just the same.
Since the speed of the clicking changes with engine rpm, is my whole electrical system ****ed? Or could a faulty ground cause that? I'm going to go change the ground for the amp right now, even though it looks great.
Any ideas? Thanks for looking.