I have a house pre-wired with coax cable for the purpose of distributing audio speakers around the house, but I cannot find a connector or adapter that splits the coax cable into the +/- wires so that I can connect the speakers
Are you sure that the COAX was installed for AUDIO? I don't think anything of the kind exists to split coax in +/-. An RF modulator will change a composite video audio signal for a TV into a VIDEO RCA plug and TWO AUDIO RCA plugs, but the signal going into the wire would have to be that type of composite signal that a TV uses. My knowledge is hardly exhaustive, but I have a friend here that is a specialst in Car Audio, and he has never heard of it either. If you have any luck, post the answer again, I'd be interesting in learning about it.
While an adapter to convert the coax into a +/- connector exists, I would not assume that the coax was installed for speakers. I would assume it was installed for television reception. Where does the coax run between? Does it come from a common point and run to various rooms. If so, I would say that this would be for TV. The common point would be the feed from the cable or satellite company. For speaker use, there would have to be 2 coax to each room, for left and right speakers. The link below shows a coax adapter to seperate wires.
