Voodoo Lab

hello,
I am running two boss EV5 expression pedals through my GCP. they both work fine, until recently I've been hearing zipper like noise through my amp whenever I move my pedals. not sure what causes this. any idea?

If this just started happening, then most likely there is a failing shield on an audio cable somewhere in your setup.

Are the Ground Control Pro and the two expression pedals the only things out on the floor? Are they mounted to a board or anything metal?
What are the MIDI devices in this system? If there are many devices then try breaking the rig down to the simplest setup that still yields the problem.

I hope that helps!