I've heard it claimed, and I have read some claims, that you will have better sound from your stereo if you purchase premium speaker wires. These products, we get told, will reduce the amount of noise that will ride along on top of your treasured recording of Rossini's "Duet For Two Cats".
For a little fun with that musical masterpiece, see the YouTube video below
Afterwards, check out a few more sites. There are some great performances of that composition waiting to be heard.
In any case, I decided that this kind of claim merited a look-see.
Copper wire of 20 Gauge will provide a resistivity value of 10.153 ohms per 1000 feet. Let us assume a pair of copper conductors feeding a 3.2 Ohm speaker at a distance of twenty feet from the stereo. We want to see how wire induced noise would compare with the listening level.
The total copper length will be twice the separation distance which comes in this case to 40 feet. At the stated resistivity, the resistance will be 0.406 ohms. At an assumed room temperature of 300°K, the wire will deliver a Johnson noise voltage of sqrt( 4kTBR ) where k = Boltzmann's constant, T is temperature in degrees Kelvin, B is bandwidth in Hz (which we will assume here to be 20000 Hz) and R is the just now calculated wire resistance.
Numerically, we assume for the speaker, and we find for the wire as follows:
The wire's Johnson noise which is more than 150 decibels below the speaker's signal level is simply not going to be heard. Period.
Buy the cheap stuff.