So I've grounded my cable tv to the water main (along with my mains), I've checked every cable connection, inside and out, to make sure they were properly fitted, I only have one splitter for the three TV's in the house, and I can't get the hum to stop. Granted, it's only audible from about 2 inches away from the speaker, but I'd like to get rid of it completely. If I remove the CATV from the wall the hum is gone, so I know it's being caused by that. So what the hell is going on??