Connecting sub via pre out RCA connection

[CurlysYamaha]

I have a Yamaha RX-V465 receiver and I am trying to connect my Polk 10" sub. My pre out sub connection (single black) doesn't seem to be working when I run the sub cable through a spliter to connect to the RCA (red and white) inputs on the sub. So, I used an RCA cable and connected it to the pre out RCA connection on the receiver and ran it directly to the rca inputs on the sub. This seems to be working, but I am concerned that this is not correct and could damage my new sub. Any thoughts? Bad spliter?

 

[americanaudiophile]

Did you go into the receiver speaker menu and set the subwoofer to "yes". That will turn the subwoofer output on. Set any speakers that don't handle bass to small.
Using the preouts won't hurt the sub but when you turn the subwoofer on you set other speakers to small so that the bass is routed to the sub. Allows those speakers to play cleaner and louder.
And you don't actually need the splitter with the sub out (just use either input) but it's fine to use it.