If you have cable, you may want to make sure your incoming cable is properly grounded ... in my case, I ran a 12ga ground wire from the splitter (inside the plastic box in the pic) for the house down to the house grounding rod. Just a month or so ago I noticed a very prominent ground hum and went outside to check the ground, sure enough the wire had somehow worked itself loose from the rod and after securing the wire the ground hum disappeared.
Which reminds me, I *really* need to secure that ground wire to the house one of these days.
