Toggle between two audio devices on macOS as a shell script. Set the devices on line 11 and 12. Requires Homebrew to be installed in the usual directory.

toggleAudioOutput.sh

#! /bin/bash
# Author: James W Mann (jwmann)
# Dependencies: homebrew, SwitchAudioSource (https://github.com/deweller/switchaudio-osx)
# Notes: If SwitchAudioSource, the script will install it automatically
#        See all audio devices: $> SwitchAudioSource -a
#        Manually switch with: $> SwitchAudioSource -s device_name

toggle_audio() {
  brew=/usr/local/bin/brew
  if [ -f $brew ]; then
    switchAudioSource=$($brew --prefix)/bin/SwitchAudioSource
    if [ -f $switchAudioSource ]; then
      currentOutput="$($switchAudioSource -c)"
      audioOutputA="Vanatoo T0"
      audioOutputB="Built-in Digital Output"
      case $currentOutput in
        $audioOutputA )
          switchTo=$audioOutputB
          ;;
        $audioOutputB )
          switchTo=$audioOutputA
          ;;
      esac
      $switchAudioSource -s "$switchTo" > /dev/null 2>&1
      osascript -e 'display notification "'"${switchTo//\"/\\\"}"'" with title "Audio Output"'
      return 0
    else
      osascript -e 'display notification "SwitchAudioSource binary not found. Installing now." with title "Error Switching Audio"'
      $brew install switchaudio-osx && osascript -e 'display notification "SwitchAudioSource binary successfully installed." with title "Audio Output"' && toggle_audio
      return 0
    fi
  else
    osascript -e 'display notification "Homebrew not found. Please install homebrew." with title "Error Switching Audio"'
    return 1
  fi
}
toggle_audio