Occasionally read things about this, but never had the problem so didn't pay attention. Set up my system last week and all was well until I connected the DVD player and projector - sub hum. Now this is on the mission FS1-AV sub, and it even does it when the receiver and DVD player is switched off. Can anyone provide some initial guidance of where I should be looking to avoid this? It isn't loud, and I'm currently switching the speakers off after viewing. but that isn't very convenient and I'd like to try and get rid of it.