Yes. Using optical cable for 5.1 audio is the way I used and experienced at my friends home theater setup. Its my observation that if you choose dolby digital for audio, you will get only audio for HD channels in
TV.
Regarding the type of cable, I presume that you are using
Tata Sky+ HD and if I remember correctly the STB has both optical as well as coax for digital audio output. If so try using any RCA audio/video cable which you have or came with the STB to make sure that you get 5.1 audio. And then go for purchasing optical or coax cable. IMO any optical cable should work flawlessly for good audio quality. A branded one may last longer. Thats it.
I recently bought a
LG home theater system (LG HB806TM) and a
Panasonic Plasma TV (VIERA TH-P42X30D). In the HTS, there is one HDMI out port but no HDMI input port. So I have connected HTS with the Plasma TV using HDMI cable and it works great. I have also played Blur-ray discs on the HTS and and the 5.1 audio quality is awesome.
It was all great, but I started facing a problem when I bought
Tata SKY HD STB, hoping to enjoy the HD quality viewing and 5.1 channel surround on the HD channels. Tata sky has provided one HDMI cable (along with other cables that they usually provide), which I am using to connect the STB with the Plasma TV. I could anyways not use the HDMI cable to connect to my HTS, as it does not have any HDMI in port.
Now, Tata HD STB does have a S/pdif coaxial out port to give 5.1 audio to an HTS, however, the second problem is that my HTS only has a TOSLINK optical input port. There is no S/pdif coaxial in port in my HTS. I know there are converters available that convert coaxial into optical, but the cost would almost be equal to a new TATA sky HD+ STB (which does have a TOSLINK optical output). Had i Known this, I would have bought the HD+ STB in the first place. I am not sure why would Tata sky have different ports on both the HD boxes.
Now, I though a lot about a convenient solution, but I am not sure if it will work.
The specs for Panasonic VIERA TH-P42X30D, does show that it can play digital Dolby (though it obvious does not have the 5.1 speakers to give the effect). Also, it does have a TOSLNIK optical output. So if i connect my Plasma TV (which is getting Video and Sound input from STB throgh HDMI) to the LG HTS using an optical cable, will it give the same 5.1 channel surround effect, which I would have otherwise got (had i been able to connect by STB with LG HTS directly).
I would really appreciate some help on this.
Regards,