I picked up a nice Xmen pro this weekend. It works great but has one issue. There is a loud humming/buzzing noise all the time. I believe it is coming from the subwoofer. It definitely is not the backbox speakers. I also checked all the coils and none are energized when they shouldn't be. I tried lightly pulling/moving the subwoofer wires and the noise changed pitch but won't go away. Any suggestions?