I have been following your discussion, or lack of it, because I am thinking of doing the same thing due to the very poor sound quality of my flat screen TV's. I afraid I am not an audio/electronics expert, but my on-line research leads me to believe that to connect from a TV digital co-axial outlet with a digital SPDIF signal to a set of normal analogue speakers, you will need a converter box, several types are available From Amazon. You would presumably connect the box to your TV via a co-axial cable with RCA type ends. Perhaps someone who really knows what they are talking about can confirm this or put me right? ChrisC.
Probably the best thing to do is to buy a new tellybox with really good speakers already screwed (or glued) into it and then you'd have a brand new Tellybox (or TV as some people call it) with a far better sound than your old one. Your telly might be so good that you'd save money by not having to go out and buy popcorn at overpriced prices at your cinema. That's what I'd do anyway.