Final Cut Pro - Creating Multiple Track Audio Output
Here's how to assign different FCP audio tracks to multiple outputs.
By default, Final Cut Pro creates a single stereo pair for audio out.
However, it will allow you to create up to 24 tracks of audio out using Sequence > Settings > Audio Outputs.
Once you've created the number of output tracks you need, you still need to assign each Final Cut audio track to an output.
To do this, Control+click between the A1 patch and the padlock icon on the left side of the Timeline. Then, from the pop-up menu, select the output channel you want to assign for that track.
Note: Final Cut does not allow you to assign the same track to more than one output. You can, however, assign multiple audio tracks to the same output.