Where to connect the sense wire when installing a sub in a 2005 Prius?

Hi everyone,

I am interested in installing Kenwood's KSC-SW10 subwoofer in my 2005 (JBL System) Prius. I have seen a couple of postings where it is installed inside the plastic bin below the carpeted trunk, but above the spare tire, and I would like to do the same. A couple of questions as it relates to wiring:

1. Is it necessary to splice the sub's input wires to both rear door speakers? Or is tapping in to one of the door's speaker enough? Any idea what color the Prius' speaker door wires are? I know there is a bundle of them in there.

2. Where is a good to splice the sense wire into, that is not too complicated? I obviously do not want the subwoofer powered when the car is not on. Especially given the size of the 12 v battery.

Thank you very much for the replies. Looking forward to this project and to improving the sound in my Prius.

Chris