Reddit mentions of VicTsing RJ45 RJ11 Cable Tester Telephone Wire Network LAN TV Cable Electric Cable Tester Wire Line Finder Tracker

I'd advise asking over in /r/hometheater. I have a pretty good idea what you'll need to do (though I can't see the pics here at work) but those guys know their zoned music systems. Are the cables/connectors labeled or are they just sporadically strewn throughout the house?

Edit: Now that I know which sub I'm in (I think that I thought it was /r/homeimprovement) do you have a wire tracer? They're great for any and all wiring jobs. I have something similar to this one because I mostly use it for low voltage, but with the alligator clips it works fine for electrical wiring and, in this case, speaker wires.