John, I double checked just to be sure and I used only the preouts from my Onkyo TX-NR709. I've been hooking up my own gear for years and have heard ground loop feedback on some amps I've had through the years. It only took a simple filter to fix it. The difference here is that I have no sound other than the loud hum. I have unhooked all the individual cables to check for a bad cable. I'm leaning toward a amp issue on this one.