I want to build a home system, build my own speakers, enclosures etc & would like to use a car stereo as the central unit for the radio, CD & Aux input (for MP3 player), I don't plan to attach anything else, just want to build a standalone audio system. I believe this is possible as I have seen in Car Dealerships & Motor Parts Retailers displays of different stereos obviously powered by mains. But how do I connect it all & what would I have to do with regards to differences in voltages ie. UK Mains=240 volt & Car Stereo=12 volt