No offence, but I think a few members really need to do a bit of basic reading on electronics to understand AC and DC current.
Without getting bogged down here, DC (direct current, or fixed polarity) is what takes the information from source to preamp, preamp to power amp, down digital cables etc. AC (alternating current, which constantly reverses polarity at either fixed or variable frequency) is what brings mains power to your system, and what carries the final signal to your speakers. I believe it's also what carries the signal from a TT cartridge.
Polarity is VERY important in DC circuits, and there is some evidence that such cables can perform better using directionality, especially where filtering is involved.
However, there is simply no point in directionality in AC cables, as there is no fixed direction of current flow, and hence no true polarity. The only reason we have + and - speaker wires (which probably confuses the issue) is to prevent the speakers being wired OUT OF PHASE with each other, which is detrimental to the sound to say the least!
As someone above pointed out, the only possible reason is if the cable has shielding and this needs to be attached to a particular component (eg. the amplifier or TT).
It would be refreshing to read something more creative than "try listening and you'll hear a difference" every time another member actually uses physics or electronic theory to back up an answer. Sometimes this forum gets a bit "Evolutionists vs Creationists"!
