When I bought Supra Quadrax loudspeaker cable (which are tin plated copper wires) gave for me the best most neutral souding audio quality.
Copper always sounded a bit warm for me, Supra Tin plated loudspeaker cableswere the best choice for me.
Later I experimented with using solid copper coax cables for making my own interconnect cables, I made a set of 50cm interconnects for my father audio set, and the quality was impressive, solid wire seems to give the music more foundation, the music sounded more solid, better bass definition, and still de details were very present. the cables are more fragile because of the solid stiff core, but I can recommended Audiophiles to experiment with it, the shielding of the coax cable is a bonus, and the price is with 1 dollar a meter a bargain