

To include FocusRite mic input in HDMI audio output with loopback:

pactl load-module module-loopback channels=1 latency_msec=1 sink=alsa_output.pci-0000_01_00.1.hdmi-stereo-extra3

The see All Streams in Recording tab of PA Volume Control



To remove loopback later:

pactl unload-module module-loopback


To send audio out to both HDMI, use paprefs and set up a virtual device that
outputs to both.
