[gchappel]

Speaker cables can certainly change the sound of your system. Some cables are brighter, some will sound quicker- some were boomy and sounded horrible on my system. I found no correlation with sound and expense. Try a handful of different cables if you are looking for that last 1% of what you consider to be a glorious neutral sound.
Analog interconnects make a little difference, I think. The differences are so subtle, at least on my systems, that I really can't confirm differences. I ended up making my own out of 25g silver. They may be better than the ones that come in the box.
I have been unable to tell any difference in digital cables- except some are too short.
Gary