The torroidal transformers in the Outlaw equipment seem to be pretty sensitive to any DC component on your home power lines.

I "solved" my problem by getting a power conditioner to give me a nice, clean power. However all I really did was move the hum from the amp to the power conditioner. This works for me because I am able to hide my power conditioner and can't hear the humming.

There was a noticeable improvement though because when the amp was humming some of the noise was coupling into the speakers and I could hear it during quiet moments in the soundtrack. No audible humming now.