Set the channel strip output format
Logic Pro X can automatically determine the output format of specific channel strip types. You can override the automatic choices by manually setting the output; otherwise, the channel strip output formats follow these rules:
Audio channel strips: The channel strip of an empty audio track is automatically set to the format of the first audio file added to it. If you add an audio file to a track assigned to a different output format (adding a stereo file to a track routed to a surround output, for example), the audio file is automatically upmixed or downmixed to match the output format of the channel strip.
Note: The highest possible surround format is determined by the project surround format. See Set the project surround format.
Instrument channel strips: Instrument channel strips automatically adopt the channel format of the inserted instrument.
If you insert a stereo instrument, the channel strip output will be stereo.
If you insert a surround instance of a software instrument (ES2 or Sculpture, for example), the channel strip output will match the project surround format.
Aux channel strips: Automatically created aux channel strips adopt the format of their input source (if a stereo channel is routed to an aux channel strip, the aux will be stereo). If you manually change the output format of an aux channel strip, Logic Pro automatically:
Inserts a Surround Balancer or a mono/stereo to surround panner, if you are changing the output of an aux from mono to stereo or mono/stereo to surround. See Surround Panner overview.
Downmixes the signal to the required format.
If you don’t want to work with the automatic settings, you can manually set the output of all audio, instrument, aux, and output channel strips to the chosen project surround format.
Set a channel strip output format to surround
Click-hold the Output slot of the channel strip, then choose Output > Surround from the pop-up menu.
The Pan control of the channel strip is replaced by a two-dimensional Surround control. The loudspeakers are represented by colored dots and the pan position is indicated by a white dot that can be moved. For more information, see Surround Panner overview.
Set the output format of multiple channel strips to surround
Select all channel strips that you want to set to surround output.
Click-hold the Output slot of one of the selected channel strips, then choose Output > Surround from the pop-up menu.