I just bought a gcx and ground control pro. My rig consists of just a few pedals, a fender twin reverb, and my Mesa dual rec. I'm having trouble setting everything up for the channel switching. I've been reading about the amp gizmos and everything but have decided that I'll wait on that since I'm only running a few pedals at the moment. I've been running out the external switches in the back of my dual rec into the out of the loops, I've been getting this loud, almost hair clipper, kind of sound on channels 1 and 3 with no other audio coming out. I'm not sure if I have everything hooked up correctly or if I just don't have a setting set right. Any help would be appreciated.

Thanks.

You should be sure that no other cables are connected to the GCX loops being used to change the amp channels. Only the Out jacks of these loops should have a cable connected.

I hope this helps!

Nothing is plugged into those loops but the channels. The amp wants to select two channels at the same time.

You have to use the Ground Control Pro presets for channel changing because the amp has no internal logic. Basically you have to set it up so only one of the switching loops is active at any time.