Here is the setup : SkyDigi dish+lnb & NTL Cable co-ax fed into an active splitter which combines both cable and satellite signals and sends them to up to 10 locations around the house. There is no earth connection on this active splitter. It works great - I can feed multiple TVs and SkyDigi boxes. This splitter is located in the attic and all my co-ax cables run to and from there (including the co-ax feed from NTL which terminates in a box along the outside of the house). At each TV I have three-way boxes that split the signal into TV / Satellite / FM radio. My home cinema is in a converted garage and the electricity is on a separate circuit to the other rooms in the house. Here is the problem : I take the co-ax that runs from the active splitter in the attic and appears in the home cinema and connect it to the Marantz receiver. I get very loud audio hum. When I connect to the VCR in order to view TV stations I get a 'hum bar' on the image from the projector (a faint line/bar that moves up the screen). Gordon from StereoStereo very kindly sent me a co-ax ground breaker. I tried this but it didn't work - I didn't get any signal at all on my Sky Digibox ("no satellite signal being received") and it didn't fix any of the other audio-video problems. (Off the top of my head I cannot remember if I even got a TV signal on my VCR). I know this is some kind of earthing problem but I don't know where to begin - should I try to get everything going to the same earth/ground ? (does the active splitter need a ground connection ? should I try to use the same ground connection for the household electricity supply ?) Advice/Tips welcome.