Copper Is copper . In North American they are about a hafl dozen manufacture of copper. They sell it other company who redraw down to a gauge or size wire. The number of strands of wire makes speaker wire speaker wire. Electrons are electrons they flow alonge the outer part of the crosssection of the wire, not down the middle of the of wire. That is why 14 gauge romax NX (wire used for your home electical circuit 120V 60Hz) is not good for speaker wire its is one strand wire, Building wire 14 gauge THHN is better because it has more strands ( 7 to 9 ). Speaker 14 gauge wire has a higher number of strands and the more stands will usely mean a high price for the wire or cable. I over simplify this but because of low voltages, and frequency going from 20Hz to 20KHz at every high rates of change you get a better signal in stranded wire. The place to put you money is in the connection. A bad joint or connection has more to do with bad sound the the difference in the price of the wire.