Audio Outputs Tab of the Sequence Settings Window
The number of output busses specified in the Audio Outputs tab determines how many
QuickTime audio tracks or AIFF files are exported. However, the Config pop-up menu can
modify whether all output busses are exported individually or as a stereo mix.
Each mono output bus in your sequence is exported as an individual mono QuickTime
track or mono AIFF file. Each stereo output bus is exported as a single stereo
QuickTime track or stereo AIFF file.