converting three RCA wires; home theater

Can you merge the negative wires on RCA cables that will connect a stereo preamp and a stereo amplifier? I want to place components in two different parts of the house and connect them through three RCA cables that were preinstalled in the house that exit in either location. I will need to connect the equivalent of two components, one from point A, where I will have a receiver, to an amp in point B, and one from the receiver in point A to another amp in point B. The problem is that, I have only three RCA cables installed within the framing of the house, not four, as I would ordinarily need. I figure, if I can share negative wires in both directions then I should be able to modify the RCA cables to do this, but otherwise I'm stuck.

If I understand, you want to send two different stereo signals down three RCA coax cables so that each amp can play a different source?

If so that means you would need to send a signal down one of the shield connections, and that probably won't work. You could try, but you will likely get significant hum.

EDIT: If you need a second audio path you might use a wireless connection such as one of these **broken link removed**.