Can digital cables be used as interconnects?

Digital cables are made with a different impedance and so are optimized for dighital pulse transmission. But they will work for audio, perhaps not optimally. You won't hurt anything. Try it.

No, But they can be used for component video. You'll need three. Having an old set of High Quality (slim pickin's) comp video cables can make three digital cables. Good to use for cable box or XM reciever.

I've used Speltz anti-cables both ways, sounded good both ways.

In my Wire World Cables review for Dagogo.com I do precisely what you are wondering, and I share the results. Since that review I have continued to use a pair of Golden Starlight Digital Cables as ICs for my twin Pathos Classic One MkIII integrateds running mono. It is a tremendously rich presentation and I find that if there is any decrease in detail it is so slight as to be almost negligible. Meanwhile, the body and richness they afford is remarkable. They have an effect not unlike putting a tube preamp into a SS system. With some equipment it is a glorious result.

It is definitely worth the effort to try. It should not hurt anything to do so, and you may very much enjoy what it does tonally to the presentation. It is a curious experiment which might shock you at the outcome.

I have not tested this out with other brands, but with this pair of Digital Cables the results have been so positive that I usually try them on any rig I set up just to see what will happen. Also, on very high end rigs moving them to different locations in the system can influence the sound.