Can you get a wiring diagram on line or from Klipsch?
There is no standard for the pins. The cable you show, I'm certain is not the right one.
You might be able to locate the input pins, by touching each pin with a small metal handled screw driver and see which ones make the sub buzz when it is on. That will tell you which are the inputs. Then you could make up a lead.
Your other option is to take the sub apart, and see where the connections go, and them change it over to RCA sockets.