"There are two rules to follow when it comes to choosing speakers: distance and power. The bigger the distance is between the amp. and speakers, or the more powerful your system is, the thicker the cable should be. In most cases, a cross section of 2.5 mm2 is sufficient, but with a distance greater than 10 metres, it is recommended to take a thicker cable. By the same token, if you’re planning on installing a powerful system, based on a processor and separate power supply blocks, you will also have to consider a thicker cable.
When it comes to sound quality, it should be said that each cable possesses its own particularities that provoke an accentuation or attenuation of certain frequencies. Indeed, cables are generally made from copper which is more or less pure… in other words, it has traces of other metals mixed-in, and different sound frequencies are better carried by different metals. It’s for this reason that manufacturers also propose speaker cables made up of several metals platted together. You can subsequently slightly alter the sound quality of your system depending upon the cable you choose.
This being said, don’t dwell too long over countless cable tests to find the "exact" qualities you want. We’re only really talking about nuances which are only really important in a real top-line system, and to appreciate the difference, you need a good ear and plenty of spare time!"