Go for precious metals -
silver is good, gold is better!

Copper is a good electrical conductor but silver is better.
However, conductivity is not the only parameter that counts when choosing conductor materials for high quality audio cables and wires.

Conductor materials for Dual Connect cables are chosen in support of our theory that it is very important that electrons are easy to move away from the atom. This results in an easier flow of electrons through the cable - an easier flow of the music signals. The result is a more dynamic, a cleaner and a more detailed sound, without cable conductor distortion.

I order to develop our theory, we studied the atom construction of those conductor materials that might be applicable for audio cables.
The condition for a material to even be considered was that it had exactly one electron in the outer atom electron-orbit. If only one electron is present in the outer orbit, this electron will be easier to move away from the atom - easier to make the electrical current flow through the material.
Secondly we were looking for materials, where the outer single electron is as far away from the atom nucleous as possible. The further away from the nucleous, the easier the electron again is to move away from the atom.

We ended up with three main contesters: Copper, Silver, and Gold.

Gold is the better of the materials (see figures on the right) because it has one electron in the outer orbit, which is one position further away from the nucleous than is the case for silver. Silver is in the same way better than copper.

CONCLUSION
Ranking of audio cable conductor materials:
1. Gold
2. Silver
3. Copper
So all audio cables should be made with pure gold as the conducting material!!

HOWEVER
For speaker cables it is required that the total resistance is kept at a minimum in order not to influence the damping of the loudspeakers. In other words, even using a good conducting material, a certain cross-sectional area is required.
Gold is 50-100 times more expensive than silver, so building speaker cables of solid gold would result in costs that only very few people would be willing/able to accept.
This is the reason why Dual Connect speaker cables use solid silver as conductor material, while our interconnects and signal wires use solid gold.