For the past two years I've been running my Onkyo TX-SR600 with just front, center, and subwoofer. I've been able to crank the volume with no problems, sometimes as loud as 78. However, I just moved my unit downstairs to my newly built home theatre room. I have the speaker wires running into a wall terminal with surrounds and rear center hooked up and now when turned up as low as 48, my receiver goes on standby and says "protect" after I turn it back on. I don't know if resetting the unit will solve this, because I now have more plugged in, but I've never had a problem with this before. I don't see any frayed wires or anything like that, so does anyone have any suggestions on how to fix this?