My subwoofer often turns off by itself when my recevier is playing at low volumes, but there is still bass comming from the sub. Why does it turn off if there is a signal but that's not very loud? I set it to always on for now. Would plugging it into one of the AC outlets on the back of my recevier make it turn on/off with the receiver? And why does the manual say not to plug any A/V components to the rear receiver outlets? I though that's what they were for.