DESC: Today's car stereos can be about more than just music. Take Pioneer's DEH-P9800BT CD/MP3 player, for instance. It's packed with all the high-end audio features you'd expect from Pioneer — like MP3, WMA, and AAC file playback, digital sound processing, and a 16-band equalizer. But this stereo also comes loaded with a built-in Bluetooth wireless receiver that allows you to use your cell phone hands-free without installing any extra gear.