excerpt from Ethan Winer’s website:

THE CABLE GUY

The earliest audio scam I can recall is fancy wire for connecting loudspeakers, and it’s still going strong. These days vendors claim their wire yields better sound quality when compared to normal wire, and, of course, it’s much more expensive than normal wire. In truth, the most important property of speaker wire is resistance, which is a function of its thickness. The resistance must be low to pass the high-current signals a power amplifier delivers, and is exactly analogous to a large water pipe allowing more flow than a small pipe. For short distances – say, up to five feet – 16 gauge wire of any type is adequate, though thicker wire is needed for longer runs.

The three other wire parameters are inductance, capacitance, and skin effect. But those are not a factor with usual cable lengths at audio frequencies, especially when connecting speakers to a power amplifier. Low capacitance wire can be important in special cases, like between a phonograph cartridge and its preamp. But high quality, low capacitance wire can be had for pennies per foot. Wire scams are very popular because wire is a low-tech device that’s simple to manufacture, and the profit margin is extremely high. I could devote this entire article to wire scams, but instead I’ll just summarize that any audio (or video) cable costing more than a few dollars per foot is a rip-off.

Even sillier than expensive speaker wire is replacement AC power cords and most other power “conditioner” products. The sales claims sound logical: Noise and static can get into your gear through the power line and damage the sound. In severe cases it’s possible for power-related clicks and buzzes to get into your system, but those are easily noticed. The suggestion that subtle changes in “clarity and presence” can occur is plain fraud. Indeed, every competent circuit designer knows how to filter out power line noise, and such protection is routinely added to all commercial audio products. Spending hundreds of dollars on a six-foot replacement power cord ignores the other hundred-odd feet of regular wire between the wall outlet and power pole./p>

Even more about cable myths here. And in Dutch here.

Also, read the letter from Blue Jeans cable sent to the biggest sham company ever called Monster Cable.