i am getting an intermitant humming coming from my paradigm servo 15 sub. the noise is actually coming through the front of the sub and lasts for varying periods, usually 15 to 40 seconds. i have used a mains cleaner, changed cables and moved the sub but nothing helps. the sounds come when the sub is "on" but not actually producing bass. it is connected to a denon 3801 amp via a phono lead, the humming used to happen with my previos amp also. has anyone had similar problems?