When you click a channel strip of any type (audio, software instrument, aux, output, master, input, or bus), the following common parameters are accessible:
Assignable checkbox: Makes the channel strip assignable from the Reassign Track shortcut menu in the Tracks area; Control-click the track header.
Device pop-up menu: Click the visible device name (Core Audio, for example) to reassign the selected channel strips to a different hardware device.
Channel pop-up menu: Click the visible channel name (Audio 1, for example), and choose the channel strip type from the submenus. This is how you can reassign a (newly created or existing) channel strip object (an audio channel strip is the default for new objects) to other channel strip types. You can choose from:
Audio: The default channel strip type, used as the destination for audio tracks.
Input: Primarily retained for compatibility with projects created in earlier versions of Logic Pro.
Aux: Auxiliary channel strip, used as send returns for all channel strips (via Sends), as subgroup channels, and as individual output destinations for multichannel software instruments (EXS24 mkII, for example).
Instrument: Used as the destination for (software) instrument tracks.
Output: Represents the physical outputs of your audio interface. You can choose either mono or stereo (paired) outputs.
Bus: Primarily retained for compatibility with projects created in earlier versions of Logic Pro. The functions of bus objects are now performed with (the more flexible) aux channel strips in Logic Pro.
Master: Only one master channel strip can exist in a project. This is the master volume control for all channel strip types (except external MIDI channel strips).
MIDI Channel pop-up menu: Choose a MIDI channel that can be used to control the channel strip.
Q-Reference checkbox: Allows you to use the transients of regions on tracks that reference the channel strip for audio quantization, if part of an Edit Group.
Flex Mode pop-up menu: Choose a flex algorithm that can be used to process the audio material on the selected channel strip.
Show checkboxes: Select the corresponding checkbox to show EQs, Inserts, Sends, and I/Os on the selected channel strip or strips.