As I said, the TOSlink input is working and should be able to handle DD, dts and regular PCM/stereo. Since it is not, I would suspect that the sources are not set up properly. If they have HDMI outputs, they probably default to sending the audio to HDMI and not to the digital coax/TOSlink outputs. Check the setups for the BR player audio and the cable box.
Kal
Kal