I was just playing my Kemper with the bass (Fender P-Bass) for a few hours and it started crackling really bad. When I stopped playing the crackling stopped. Initially I thought it was my cable or electronics. But after messing with it a bit I couldn't recreate it by jiggling and what-not. So I started playing again and after about 5 minutes I got the same thing. I noticed that my "Output" LED was in the red range when this was happening.
I am playing my powered Kemper head through an old Gemini PA cab (probably 70s or 80s model) with two 15" , a horn and tweeters. The Gemini is rated 8 ohms 300 watts RMS and 600 watts Program power . Have I been pushing it too hard?
I've never experienced this while playing my guitar, and never with my bass until tonight, although I never play my bass for more than two hours maybe tops.