ARC Cessna 328 Aux Audio Inputs

Under the supervision of my IA, we installed a vor radio. I connected
the vor audio output to one of the Aud-Audio inputs on the RT328D,
thinking this would supply audio to the intercom (connected to the
RT328 phone output) and the speaker.

The VOR radio output only appears to go to the speaker (via RT328D).
I expected these aux-audio to go to the rt328 phone output, but that
doesn't appear to be the case. I guess I need to get an rt328
instruction manual or schematics to determine the function of the
aux-audio inputs.

Any help would is greatly appreciated.

Mitch