I installed this dual channel pickup system a few weeks ago and it was working great. Suddenly I notice this buzzy fuzzy noise when I hit my lower strings even moderately hard. It isn't the cable. I've tried the cables directly into a mixer without using the preamp and there is no buzz. It happens whether the mic channel is turned on or off.

Any ideas?
Nevermind, I'm a newbie. My gain inside the preamp box was set too high.