u/Ecstatic-Swimming680

I've been playing with the Boss Katana Bass amp at church and noticed that when the amp is turned off, there is a persistent hum going through the DI to the PA system. I tried adjusting the ground lift, but that only takes care of some of the hum but doesn't eliminate it. I don't know if it's an xlr cable issue, amp issue, or that is just how it is. Help?