YouTube live mixes using Denon X1800 mixer

I am using a MacBook and trying to do a live stream of my mixes through YouTube using the USB.

When I patch the USB in Abelton and switch the channels to 9/10 (master channel) everything worked fine in that I can record a mix through my DAW from USB. Now comes the tricky part…I’d like to record YouTube mixes in realtime using the X1800 audio source through USB, but YouTube won’t get the sound captured in the stream even though it sees the x1800 as an alternative audio source (and yes, I went to system preferences to make sure input was coming in from the x1800). Do I need to use SoundFlower or Loopback (hopefully not)?

Any thoughts, suggestions, on how best to do this? I do have an Apogee audio interface that seemed to work via audio, but I shouldn’t have to use another audio interface.

What broadcast software are you using?