Your Sony XBR9 only outputs optical 5.1 DD when the set's ATSC tuner is receiving a broadcast with DD. If you are viewing something via HDMI or any other source other than OTA the optical output is 2 Channel Stereo only. You've been missing a lot audio wise if you are viewing satellite via HDMI and using optical out from your XBR to your surround receiver
Perhaps I'm not supposed to get DD 5.1 output from my XBR when viewing an HDMI input source, such as my 622, but I definitely am. When my surround receiver receives a DD5.1 signal, the display shows 'Dolby Digital', when it receives a 2-channel signal, it displays 'Pro Logic'. I can definitely tell the difference in sound quality between the two. I compared the sound on the same channel through OTA and Dish, and it was identical. Both displayed 'Dolby Digital', and the sound quality was the same. I could definitely hear the 5 channel separation on both. So my audio receiver says it is getting a 5.1 signal, and the sound that it outputs is 5.1.
I'm surprised that I'm getting the 5.1 passed through, but there is no question that I am. The only explanation I can think of is that I have the HDMI output from the 622 going through an HDMI splitter. Perhaps the splitter is not passing the DRM flags through.