I too am having an issue getting the HDRadio to play if "listen to this device" is NOT checked. I have updated to the latest Realtek driver for my hardware. The radio input is connected to the Blue connection which is line 1. I have the following in my rr.ini:
From my debug.txt:
Start Sequence: Starting Radio Device...
HDRadio---> HDRadioPowerOn: MyHDRadio.Open
Start Sequence: Starting Serial Devices...
Start Sequence: Starting Mixer...
VMC---> Set object successful
VMC---> SOURCE: Mixer line #1: "Rear Blue In"
Am I missing something?