One of those highly controversial topics.
At one hand you have people claiming great improvements in sound quality using an other cable, others claim that tons of blind testing has been done yielding invariably the same results; no audible differences.
In general the discussion ends in a flare.
Here you find a very courageous and strikingly honest guy, Mike Lavigne.
He owns an Opus speaker cable (starting at $ 33.000) and did a blind listening test comparing his ultra high-end cable with a run of the mill Monster speaker cable.
Read this.
One can debate cables endlessly, but one can also measure.
Measuring won’t tell you everything.
If you measure differences between cables it won’t by magic map into audible differences but at least you have a clue about what these passive components do.
If you can’t measure any difference but they do sound different, you might be in for some unsighted listening tests.
At a demo you do hear a difference when they swap the standard power cord for a high end one. How could it be that a power cord make such a difference?
Mark Waldrep will tell you.