remote wire for an amp ?

the PIAA foglamps I had on my isuzu rodeo was first incorrectly wired directly to the battery, there was a little light on the switch to indicate whether the fogs were on or off and overnight it would drain the battery. the car was then correctly wired to the ignition, problem solved, so its possible you don't have to wire it to the back of the radio, there may be an easier place to wire it to, hopefully someone will help you out.

amp in a Prius? I have one word for you: Optima

 

If you have the JBL system, you can tap into the remote wire on the factory amp. I used the gray wire, on the white harness closest to the rear passenger seat.

 

If you don't have a JBL system or even if you do you can use a device like the Peripheral Electronics LVT which uses speaker wire or constant 12v/ground signal to create a 12v switched power supply for your amp. A lot of high level to low level output converters come with the LVT built in now. They are fairly cheap too. Simply use a couple of t-taps on the rear speaker wire and BAM! RCA outputs to your amp and a 12v switched power supply.
http://www.amazon.com/dp/product/B0015G3V5Y?tag=priuschatcom-20www.installer.com/pdf/lvt.pdf

 

I spliced my remote wire into the power outlet at the bottom right of the center console under the glove box. It turns off/on when the car is off/on It works great for me and the plug still works.