Try this. Go to loopback. Make a new virtual device. Name it ABLETON OUT (or whatever but I find this helps visibility). Add your output device(S) in the monitor column.
Add some output channels.
Add a Pass-Thru
In Ableton preferences, audio tab, you should be able to change your Audio Output Device now to ABLETON OUT.
Click output config underneath, and select all the buttons (Which are the channels you created in loopback).
Now back in session view, pick the track you want to send to VDMX. Change the audio out pulldown to Ext.Out. Now the pull down under it should be active, letting you pick the channels that Track will send to. At this point they should show up in VDMX.
I’ll still try and get you some screenshots but give the instructions a whirl. This is also how I kinda trick Ableton into giving me more inputs without a supported hardware interface. If you can get this running from here you’ll probably get how Loopback works to get more inputs into Ableton.
Lastly, my input device in Ableton is also made in loopback. I call it STREAM LOOP, and I run all my apps audio through that in separate channels so I can pick them individually in Ableton. That includes system mic inputs, camera mics; thus the extra inputs secret I was yammering about.
Hope to hear and see great results and I’ll do my best to assist you further if this doesn’t help get you there