I know most pickups if not all use copper wire to wrap around the magnets. That does make sense copper is a good conductor, probably would create a good current. There's metals though that are far better conductors, plenty of audio cables have gold wires, why not pickups? Do those metals not sound as good, or is it just too expensive? Has anyone even experimented with the idea? Is it just overkill? I've read about pickups having too strong of a magnetic pull on strings and messing up the feel of the strings.. I would think maybe a better conductor might magnify that.