I have the HTS 2500 and everything looks fine. I am not getting a hum but , come to think of it, the Onkyo did have a ground-(I think). Should I be running to Radio Shack?

I have tested EVERYTHING on this circuit. I even disconnected my ceiling fan and changed out my dimmer switches. POP. If nothing else I am getting quite an education ....the plug idea is the only thing I have not tried. Is there some sort of adaptor that I can get and see if that works?