How to Use MainStage to Make MIDI Mappings in Ableton Live
In this tutorial, you’ll learn how to make MIDI mappings in Ableton Live without a hardware MIDI keyboard controller. To accomplish this, we’ll be using Apple MainStage’s external instrument channel strips to communicate with Ableton Live via MacOS’s built-in MIDI IAC Driver.
Create an IAC MIDI Port
MacOS ships with a handy virtual MIDI device called the IAC Driver. It enables you to route MIDI data between software applications without the need for a physical loopback through a hardware MIDI interface.
To access the IAC Driver settings, navigate to ~/Applications/Utilities, and open up the Audio MIDI Setup application. Press ?2 to bring up the MIDI Studio window.