I've already found that the hum comes from a combination of my hdtv sat box and also my computer. The sub runs awesome when I unplug the computer and cable. Each one adds hum when they are plugged back in.

Yup, that's a ground loop. They are pesky buggers. If you want you can try a 3-2 prong adapter on the sub with the sat box and computer connected to see if that gets rid of the hum so you can temporarily enjoy your system while you are in the process of fixing the ground loop properly.