Hi...a real newbie here....this may seem silly, but in my rec room, I want to be able to use two different cable receivers on the same tv because I have one receiver that has been "loaded up" with all the channels except hd channels, while box # 2 has hd channels (and not much else). I have tried to do this (feel I am very close) ....I cannot get audio on box # 2. I think if I had more than one set of ports on the back of the tv it would make it easier. What can I do to get audio on box # 2 ??