My phones aux out quit working. My phone is what I use to listen to music in my car so I needed to find an alternative to get my music to my radio. I was originally using the AUX in mod with a cord to my phone. I ran across this the other day and I thought it might be a good solution to my problem.
It turns out it is a good solution. The sound quality is not bad at all, especially for what I paid for it. If you wanted to hard wire it in to your car I am sure you could. I will eventually get around to hard wiring it in. You could get a 12v to 5v step down (I'm thinking the easiest would be to rob the guts out of a cigarette lighter to USB plug). Then you could use a 4PST switch to turn the device signal on/off so you can listen to the radio or whatever.