DJO

My fellow groovers, Hope safe & well. I am having an issue with my Markbass Amp where recently I have noticed a loud hiss. The hiss is worse if the Horn on the fender rumble is activated. I have put a link to the video below where you can here it “pop & hiss” (new band name for anyone). Would greatly appreciate anyone’s advice if they have come across this before. video; https://youtu.be/0IDd_Bk4rdM