What cables should I have to connect speakers amp and sub in my car?

Car amplifier wiring, can I connect RCA input to my speakers?

• I am installing a amplifier and a sub in my car. I don't want to tap into my head unit to connect the RCA cable from the amp. Instead can I strip the RCA cables and connect them to my rear left and right speakers? Will that work?

• Answer:

  You cannot connect the RCA cables directly to the speaker due to the fact the head unit is putting out much more power to the speakers than the amplifier expects and can likely handle on its input. But you can use whats called a line output converter to do this. These are fairly low cost products used to convert the "high level" signals of the speakers down to a level that the amplifier can handle, and and limiting the distortion and other noise you will hear through the sub woofer. They often have built in remote turn ons, used to detect when there is music or audio playing and only turns on the subwoofer amplifier when necessary to save battery power. http://www.crutchfield.com/S-O7FqxxCKVPs/g_721/Line-Output-Converters.html