Look at the power brick that came with it. There should be a label on it that lists DC Output Voltage.
Once you determine that, then an appropriate power supply can be chosen.
Chances are, it requires 12vDC or 19vDC. In either case, a Carnetix would work.
I also suggest reading the FAQs: http://www.mp3car.com/vbulletin/advfaq.php
All this informaton is located there for you to locate.