Hi I've got a Vibe Beta sub and a Marantz 4200 receiver. When I play the test tone there is no "white noise" from the subwoofer. If I watch a dvd it appears (to me at least) that its working fine. Also if I turn the sub volume up it makes a humming noise. Surely the test tone should make some noise from the sub? Any ideas? Should I be using a special cable, I am just running a cheapo phono cable?!!