as i said before, for 5.1 over optical to work BOTH the output (from pc, soundcard for instance) and the input (receiver / ht in this case) would need to support the same format. see if your ht supports a format of any sort via optical.
if you are running a cheap htib, not all even accept 5.1 via optical
unless there is support on both ends, its 2.0 stereo.
i think the dg lacks the software support, but i believe the dx does as it has ddl.
the first thing i would do is verify your ht accepts 5.1 inputs via optical first.
also, you never listed if you had hdmi input or not........
Thanks for the reply ssddx
I am giving a lengthy sort of answer, if someone has the same question it will be helpful to them as well. I have a Sony DAV-DZ510 Home Theatre System which has Optical In. This Home Theatre System has built in Amplifier which can decode Dolby and DTS Audio. I think this system does not have HDMI input but it has something called Audio Return Channel but to have audio returned through HDMI both the devices which are connected should have HDMI with ARC function. To watch bluray movies with DTS audio (not DTS HD-MA) stored in my computer, all I need is a device probably a Sound Card that can pass-through the audio which is already encoded in either Dolby or DTS. I hope this kind of discussion is going on right from the launch of the Xonar DG Sound Card.
But to make things simple, I bought the Xonar DG Sound Card which does not have DDL or DTS-Connect. And the result was exactly as I expected. I connected the Sony Home theatre and this Sound Card through optical cable and installed the Xonar drivers. I played a movie that is already encoded in DTS in VLC media player and selected the audio output device as Xonar SPDIF Pass through and then I saw the DTS symbol light up in my Sony Home Theatre.
This is simple as I already mentioned in my previous question I don't want the sound card to make any conversion of PCM Audio to either Dolby or DTS. I just want the Sound Card to pass-through any sound that comes in. And this cheap sound card made my day.
Thank you once again very much for giving solutions to my question. As you said the Home Theatre also supports the Dolby and DTS formats so no problem at all.