Hello Race

I do not think the sub is bad nor you did anything wrong. This sounds like a ground loop which is a common problem when adding a subwoofer with a 3 prong cable.

The easiest solution in solving and fixing the hum is simply to pick up a cheater plug (3 prong to 2 prong adapter) which simply lifts the ground and will get rid of the hum. They usually cost $1-$2 dollars at any hardware store. If you are not comfortable using a cheater plug here is an excellent article on ground loops.

http://www.audioholics.com/tweaks/connec...em-hum-and-buzz

Congrats on your purchase BTW \:\)

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne