I've heard speaker wires make a difference precisely twice in 20-odd years of caring about audio.
The first time, the wires were MITs with their blister-thingy, and the speakers were Martin-Logan Quest-Z's. Compared to other wires, the MITs sounded very dull.
For any technically literate person, the reason is obvious: that stupid blister had a resistor in it, and it was interacting with the very low treble impedance of the electrostatic panel to massively roll off the highs.
The second time, the wires were Anthony Gallo Acoustics, and the speakers were also by Gallo. The speakers kept cutting out. Turns out the solid-core 18AWG wires Gallo peddles are cheap garbage, and in a few years of use they developed a bunch of little breaks. Replacing them with bog standard stranded wire greatly increased reliability, with no sonic difference.