It's actually the first time I've ever used a digital audio cable as most of my equipment is from the 1980s. (And I like it that way.)
Feedback is my favorite thing.
I just hooked up the output of my computer's soundcard to its input.
This lets me listen to itunes, a dvd or whatever is playing on my home computer while I am at work or coffee.
It also lets me listen to the sounds in my apartment via the microphones hooked up to my computer, like some overboard baby monitor.
Anyway, I'm pretty happy with it.