Gotta disagree with you there, Jason... you don't want the volume on an EP350 at 50%!! That'l blow you out of the water! You also don't want the receiver at +12. I'm guessing that there's something wrong with the connection or possibly something wrong with the sub itself. One way to test it is to hook the sub directly to a CD player without any other speakers and see if it produces sound. I'd advise keeping it fairly turned down at the beginning of that test, though...

I am the Doctor, and THIS... is my SPOON!