Okay. You've slaved over your work. You've mixed and remixed everything and now it's time to finish up. There are a few things to do before you're done. The first is format—what are you mixing down to? These days, you either burn to a CD or bounce into a digital file, either a compressed MP3 or an uncompressed WAV or AIFF file. Either way you cut it, the end result is about taking many tracks and bouncing them out to a stereo pair.