I have a veldyne CT-100 that starting humming when the there is no signal going to the sub. If I watching a movie and the scene is really quite I can hear the hum. But once action starts I can't here it of course cause the sub is in action. But once there is no LFE going to the sub again hum. If I turn down the volume on the sub it stops if I crank it to more than 3-4 I hear the hum really annoying. This is a refurbished sub. Its a CT-100 box and woffer with a CHT-120 AMP. If I disconnect the singal from the receiver I can still the hum. THe sub had a slight hum from the amp and I could hear it when it was dead quite in the house. Other than that you could bearly hear it. The sub is about 9 months old and it just started doing this hum any ideas?????