A vehicle sound system is disclosed that includes a set of speakers, a head unit and a disc changer. In addition to a radio, the head unit also includes a means for playing music downloaded from a computer. In one embodiment, the music downloaded from the computer is stored in a compressed format on a removable hard disk drive. The music can be organized using play lists. Software is used to program the head unit to communicate with the disc changer. In one embodiment, the software is replaceable so that the head unit can communicate with different disc changers. The head unit also includes a control panel for operating the head unit and the disc changer.