I'm trying to hook a sub up in my 4th gen with the Bose system. I'm using the one wire harness that uses the rca outputs for the speakers. My question is where do I plug the rca wires for the amp for the sub.I have a clarion cz500 and it has 4 channel outputs but those are use for the Bose. There's 2 plugs that say sub out 1and 2. I've looked it up in the installation manual for the deck but it doesn't really say anything. Am I supposed to hook the rca cables to it or use a y splitter on one of them

 

You should run an rca cable to your amplifier that will power the sub, using both the sub1 and sub2 outputs.