[Closed] Audiophile mains cables please explain?

Following on from the HDMI thread, can anyone explain the theory behind "upgrading" a mains cable for a hifi?

Even if changing power cable for something that had "better" conductivity could improve the performance of an amplifier, surely you would have to rewire your house and possibly the connection to the sub station?

Is there anyone on here willing to make an argument that a power cable can make a difference? Has anyone actually spent good money on power cable? Does anyone actually think it does make a difference?