How do I change EyeTV’s audio input to use S/PDIF on the HD PVR?
Unlike audio settings for other devices, settings for the HD PVR are selected in the EyeTV Setup Assistant, rather than the Devices section of the EyeTV Preferences.
Re-run the Setup Assistant until you get to the screen shown in the image below, and select the S/PDIF Optical audio setting.
You should be able to continue to the next screen and then quit the Setup Assistant rather than going through the entire setup, and the S/PDIF selection should be remembered.