ahh ok I did not check the specks really..sorry.it has rca in only?...check it.sometimes the same port can be used for in and out.. <----> like this sign under the port...
or ----> that is only in.......
if this does not work then there is a way out also.......connect ur pc spekers dirctly by the above method with ur stb rca output......
tatasky stbs feed via hdmi and via rca simultaneously..I checked
if local stb..thene also no problem..yellow cable to tv..red and white to speaker..simple.
but if cable connection......in my suggestion change that to fully enjoy ur tv..
before investing an amount whatever small it may be into optical to analouge converter try all methods.....