Search the archives - there's scads of information on this subject. There are as many opinions as there are audiophiles.
My personal experience is that they can make a difference, but the point of rapidly diminishing returns comes pretty low on the chain of investment relative to the higher end. Power cords especially fall under that description and the gap is wider and more ambiguous (in terms of audible differences). A wiser investment in power is having some dedicated/isolated lines installed for your stereo components only. I don't have the knowledge to explain it, but I'd disagree with the thought behind the statement that "cables just carry the signal". That said, again, you don't have to mortgage the house to buy cables, and there are some excellent offerings at the low end that do a splendid job (Signal Cable, DH Labs, and Anti-Cables come to mind).
Marco
My personal experience is that they can make a difference, but the point of rapidly diminishing returns comes pretty low on the chain of investment relative to the higher end. Power cords especially fall under that description and the gap is wider and more ambiguous (in terms of audible differences). A wiser investment in power is having some dedicated/isolated lines installed for your stereo components only. I don't have the knowledge to explain it, but I'd disagree with the thought behind the statement that "cables just carry the signal". That said, again, you don't have to mortgage the house to buy cables, and there are some excellent offerings at the low end that do a splendid job (Signal Cable, DH Labs, and Anti-Cables come to mind).
Marco