For 10-20 watts of power, the 16 ga. wire will do alright but if you have
more power than that, larger wire will be better off. I'd just grab some 2
wire romex or other such dual cables and run about 12 gauge solid wire for
better results and use the 5 way binding posts to provide a connection.
Mark each pair of wires with a colored tape so that you can identify them at
the other end and mark the cover plates with what the connection is.
RCA connectors are designed for low power uses so using them on speakers
would be overworking the connectors badly.
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Why isn't there an Ozone Hole at the NORTH Pole?