Mackie ProFX6v3 USB 3-4 as a 2nd device within the same computer
When you want to remove the Ableton instruments from the phones output for headphone monitoring while keeping the instrument recording into the main master output: 1. In the Ableton audio settings, "Channel Configuration" select Output config and enable Stereo outputs 3/4. 2. Close the settings and go back to the main panel. 3. In the track panel and look for the "Audio To" setting. Set "Audio To" output to "Ext. Out" 4. New options will appear below. Selecting drop down "3/4". This will make that track like the external line 5-6 input. If there isn't any sound, also check mac has enabled the output 3/4. In the Mac utilities folder, go to the Audio Midi Setup app in audio devices and check that Analog output 3 and 4 is enabled.