I just bought a channel selector for my crate v50 amp and it was working fine for a week and then all of a sudden it started popping when I switch back to the clean channel when there's still noise emitting from my guitar but when it's quiet it doesn't pop. Anyone got an explanation?
Wow old topic but I will step up here.

How old are your tubes? Mine started doing that when my tubes were about shot. After they were swapped out that issue stopped for me.

It may not be the case with your amp, and it could be a number of different issues. Loose connection, Crate's switching power supply, a bad cable...