Matching Audio Outputs to Clip Items in the Timeline
You can use the Match Audio Outputs command to automatically configure your audio
outputs to match the configuration of audio clip items in the Timeline. Using the Match
Audio Outputs command is more efficient than manually configuring outputs for mono
and stereo clip items in your sequence. For example, if you edit a six-channel audio clip
representing a 5.1-channel surround sound mix into your sequence, you can select it
and tell Final Cut Pro to assign the proper audio outputs for monitoring.