I only brought up instrument cables because those are something where it's easy to hear an effect if you compare them.
You can otherwise consider speaker and line level cables for guitar gear or studio gear. Personally I can't hear a difference.
I recently changed from RCA cables to XLR cables on my Genelec studio monitors because I got them placed better so I had the right length cables. I noticed absolutely no difference even though the XLR should be better for noise and quality.
But of course some pure silver cable will make all the difference. Too bad none of that silver cable is anywhere inside the amp
look up 'conductivity' in re silver. it definitely has a sound different than most copper in my experience- and i have one silver cable, so not super broad experience. sometimes it works, and sometimes it doesnt- but generally speaking, it's more open on top, faster dynamics, and less thick sounding than a lot of copper cables- a lot of folks use it in very few strands, which im sure accentuates that too.
its not magic, its a metals properties, and you can use that, like an alnico magnet, or a large dustcap or a heavier spider, or heavier gauge strings, or a choke in an amp, to tune response.
xlrs are subject to the exact same properties, you just get better noise rejection. adding more wire is great and all, but most times its just the same wire and another cheaply made termination. im not THAT surprised it sounds the same unless youre in some super noisy studio.
and while i know what studio monitors can do, they really arent always the most relaxed or natural way to listen to music as nearfields. you can hear differences- and i think if its your main listening device its gonna be more apparent- but for me, headphone and hifi amps are easier for me to hear changes in cables than a focusrite interface into monitors. but i hear them pretty plainly into a secondary canamp for recording from the same device. maybe how my own ears work or the inclusion of the space.
again, not tryna say any of this is the be all end all and anybody NEEDS this shit, only that its another tuning strategy based on real electromechanical truths, regardless if the marketing.