I’m happy to report that SGC just released an update for the Sonic Transporter to add 5.1 and 7.1 multichannel output via its USB and its HDMI port while streaming from Roon. Please be advised that running Sonic Orbiter 2.8 on the Sonic Transporter is required for this feature.
To do this go to sonicorbiter.com → manage → settings → Roon Server and enable Local Playback
Once you have done that you need to enable the port for playback in the Roon app (on your computer or iPad). Go to settings → audio and look in the section with the IP address of your sonicTransporter.
There will be a bunch of HDMI ports labeled “HDA Intel HDMI #”. Typically you need to activate HDMI 3 but this can be different depending on what sonicTransporter you have.
If HDMI 3 doesn’t work enable all of them, play to them one at a time until you hear audio and then disable all the ones that don’t play.
Note: sometimes the HDMI ports won’t show up if they were not connected to the HDMI receiver when your sonicTransporter was powered on. Make sure you have an HDMI cable going from the sonicTransporter to the HDMI receiver and have the receiver powered on then power on the sonicTransporter