I think to simplify the connections and the wire jumble , HDMI should be used. HDMI cable can be attached from TS HD STB to AVR and then from AVR to
TV ( obviously taking care of i/p and o/p ports). This should remove the need for optical / spdif.
One question - How are SD channels handled ? Do they require a separate 2 channel cable or are the signals carried over HDMI cable for these channels as well ?