Hum in Subwoofer with trouble shooting issues

I have a Mirage BPS-S210 with a LFX-3 Crossover. I recently lost power to the room (house) from a storm and now I have a hum in the sub that I seem to can't get rid of. I do not think the sub is damamged because I have a LOT of protection (Monster AVS 2000, HTS 5100, HTS 2600, AP200, Protection in each of the Circuit Boxes as well as high end breakers) I have been swapping out the cables and I put the cables on the other sub (HSU VTF3 MK3) and I do not hear the hum, but when I return the cable to the BPS-S210 I hear the hum again. I have bypassed the crossover, still hum's. How do you "drain" a line. I have heard a couple of installers use this term. I am really looking for answers.