muttsinparadise,
I have the Axiom EP500 sub. When I first plugged it in, I was also getting a little snow storm on every beat of the sub, but on a different TV in a different room on a different circuit.
It was all due to wire management issues.
I had a coax going from my sat receiver to the TV in question. It seems that the coax was intersecting the sub cable and picking up interference.
I moved things around and isolated the sub cable from everything else at the back of the receiver and the problem went away.
If it is the cable thing, watch this video for some good cable management info. It's a really good DIY cable video and there is a good cable management discussion at the end.

http://revision3.com/systm/avcabling

Good luck