Quark, if you really had that name you couldn't have become anything but a physicist, could you? The only point of significance on your speaker cables is that their resistance be negligible in comparison to the impedance of your speakers. Bear in mind that all speakers have over 100 feet of wire( cheap wire! ) inside with gauges running in the 20s and 30s. A conservative rule is that the cable resistance shouldn't be more than 5% of the speaker impedance. In your case a 6 foot run of even 20 ga would have a total resistance of about 0.12 ohm. Copper is the ideal low-resistance relatively inexpensive material for conducting electricity. Silver has an even slightly lower resistance, but it's absurd to spend the money when copper supplies the low resistance so easily.
