I have a Powered Subwoofer. Where would be the best place to tap into the speaker leads?

The setup I have just needs me to connect 2 channels into the sub amp as opposed to the RCA route.

Where would the best place to be to find the rear positive and negative channel leads?

I could run straight from the head unit, or tap in from the rear door speakers themselves,Also, what color are the left and right speaker positive and negative wires?

I would imagine you guys might know the best place for me to find the rear positive and negative speaker leads, for example, possibly right under the carpet in the harness bundle leading into the rear doors etc. Any help would be extremely appreciated!

Anthony.

 

Yes, I have JBL. Thanks so much for the info! This should do it!