Although @Almarg is probably right - in that the s-video cables may just get a little warm - I do not believe 26 or 28 gauge conductors will effectively deliver the full audio spectrum.
What length would the cables be? the longer they are the warmer they will get
Very Basically - thicker conductors + higher quality copper = better sound
But it becomes much more complex when you start to consider cable geometry - take a look at...
http://image99.net/blog/files/a8fe12e6b9c434f03264a1a90f441ff7-62.html
http://image99.net/blog/files/d048bbacfce9bcad4a025be804771d9a-76.html
The links above cover a single geometry, there are many more, e.g...
- conductors of varying size
- braided
- complex multi helix designs
- the list goes on..
Hope that helps - Steve