Okay ...
Tata Sky team seems to have changed some things from the backend. Now all three HD channels have 5.1 sound coming (till day before yesterday only Nat Geo was on 5.1)
My current wiring is as below
HDMI1 - Between my LCD
TV and
TATA Sky HD Plus DTH
HDMI2 - Between my LCD TV and Home Theater System
Coaxial Cable - Between Tata Sky Plus HD DTH and Home Theater for 5.1 surround sound system.
To check you are getting 5.1 sound or not ...do a simple thing ...
1) Mute the volume on TV
2) Select aux in on the home theater (now you can hear the tv volume through home theater)
3) Keep reducing the volume on set top box to zxero (dont press the mute button on set top box - just reduce it to zero) - you will still be getting 5.1 output from home theater right now because of coaxial cable.
The sound from coaxial cable is coming for all 3 channels right now for me - Star TV HD, Nat Geo , Discovery HD.
Please let me know if i am correct ...or if something is wrong