I just got a Definitive Technology CLR3000 center channel and it kicks butt. That's beside the point. This center channel has a 10" powered subwoofer and it is completely quiet when it is automatically turned on (with signal sensing). However, when it doesn't get a signal any more and it shuts off, the woofer starts to make a slight humm/hiss noise. It is very slight, but enough to bother me. It actually sounds like the white noise that is made when you test your different speaker channels. I don't think it is ground loop hum, because I have had that problem before at another home with different components. Any advice out there? I tried switching the three prong to a two prong - no difference. What makes it so strange is the noise is only there when the sub is turned off (the red power light on the back goes off).