I've been searching for an answer to this question as well. I'm going down the path of using the "Control4 AV Path Setter" driver as described by @Cyknight in the following thread. The documentation for the driver indicates that it sits between the device and what it is physically connected to and provides insight and provides control4 hooks for various translations. This would model the audio extractor that is physically used to down convert the audio into stereo to feed into the audio matrix.
I will hopefully get a chance to try this out soon to confirm if this works. If you get