Alright tonight I began recording with some of my new Christmas equipment. When we started I noticed a loud humming, that was not there when I was using my amp.(I was going Direct) I was using the following Tuner-> ADA Midi Preamp-> Behringer Compressor-> XLR output to board. Just now when inspecting the equipment, I noticed that the compressor XLR output has no Ground Lift/Ground switch. I am pretty sure this is the problem, but I do not know how to solve it. I need help and fast. Anyone have any suggestions on how to solve this problem?