Humming sub.

Make sure the cables don't cross over anything else.
Try plugging the amp into a different outlet? Mine really likes a line conditioner.
Definitely try different interconnects/cables. Move the sub closer if you have to just to try different cables.
My guess is that the amp & sub hum even when the pre/pro is turned off?
Playing with that much power can cause issues...

I sent this trick to a friend who had a humming Sunfire sub that many said needed to be internally rewired.
Here is what did the trick.
Take a thin run of plastic coated wire from Radio shack, find a screw on the metal plate of the sub and attach one end of the wire.Now take the other end of the wire and see where in your system the hum stops as you touch the chassis of your components.When this didn't work I told him to touch the screw on the plastic plate cover where his sub was powere at the wall outlet. I did this to get hum out of a Phono stage.Bingo, no hum from the sub.

One of the best places to search for this hum is in the video section of your system (TV, DVD, VCR, etc). While the sub is on with no music just hum unscrew your cable TV from the wall and see if that does not get rid of your hum. I had the same problem and that was it. I just happen to have a ground breaker for my cable and now it is gone. Another thing that works great is one of those filters that you buy for your car system to keep the alternator noise out. Put that on the problem and that will work. Of course, you will loose some of your sound quality with the cheap interconnect wires on it but you will have NO noise. Hope this helps and if someone else said these things already forgive me.