Hi,
I have a diff setup with my Tatasky HD, Onkyo AV and Panasonic Plasma
TataSky HD --> HDMI --> Onkyo HDMI (In:CBL/SAT)
Onkyo HDMI (Out) --> HDMI --> Plasma
This way I play TV volume (via HDMI passthru) and when I want to play sound via AV, then I just switch on the Onkyo and select the correct Input (CBL/SAT).
This does not need an Optical cable and only one HDMI to my TV.
Hope this helps too !