If anyone can tell me where i can get 12V power if the CD changer tjat mounted in trunk. I don't where can i get the switched power wire and battery power wire?

Frist i don't know anything about AUDIO, but i like to play around with my 02 type S. i just got a blitzsafe and perception digital 20GB Hard drive which can play Mp3 and more. It have 1 RCA input and 1 RCA out put which workperfect which the blitzsafe. IT's basically is like the cd changer but