Subwoofer buzzes when the system is off, what to do?

Have a slightly older 5.1 system of sony am so far for home use really satisfied, but when my xbox goes out and thus the amplifier goes out, the subwoofer growls. Suppose that he gets no more mass and therefore hums the amplifier. But do not want to tell the wrong story, can help me jmd that annoys me pretty much in my setup.

Ok, that is a tip without any responsibility.

I once worked at a stage engineering company and there were often times "bad" connections at open-air events with everything possible on the net. We then isolated the grounds with Gaffaband at Schukostecker. But this is not a permanent solution, so you can at least see if there's a Fehlerstromfluß or influencing. If so, an electrician should install a break. For example, If the neighbor's washing machine can cause a hum during drum running, which is rhythmic, but also permanent appliances that are not cleanly separated in the house, can lead to such noise hum.