I just received my mti2, I noticed that I am getting the dreaded ground hum, when the monitor is on. I have it in a furman power condidtioner but that doesnt help, I even ran an extension cord from across the room I still get the hum. I have made sure that the power cord is not crossing my audio cables, I have a very clean run. Is this normal? do I need to get a ground lifter for the Raven?