Do your ears deceive you?

The cables question is ill-formed.

I would agree that there is a difference between the worst and the best. There are many physical properties to consider: Resistance; Capacitance; Inductance; Dielectric Absorption; RF rejection; connection integrity..

So yes, there are differences based on physical principles, and understood to physics. Are they important? Yes - but system dependent. If you seek transparency, then that's easy - decent connectors and quality cabling like Canare will set you up nicely, and be somewhat better than lamp cord.

But, for example, if you have an over-bright system, then a high resistance, high capacitance, high inductance, high DA cable may correct it to the point of listenability. Of course, you might do lots better with better components, but cables do make a difference. They are just the worst way to do it. IMO.

@steakster I can't believe you are calling out some of the biggest shysters in the industry as credible.  I'm surprised you didn't include Ted Denney.

As for the rest, I do NOT, under ANY circumstances, believe that any of these companies do anything more with Quantum-whatever than misquote, bend and stretch truth, and use to deceive gullible audiophiles with meaningless word salad and pseudo-scientific nonsense.  Some of the claims of these companies are so preposterous that it is astounding that ANYONE would believe them.

        The site has yet another runway builder.

         May as well try teaching a box of rocks,

                       To sort your socks!

      Many cable manufacturers are using the results, regarding the following mentioned science, as guidance in building cables for audio systems.

        The only experimentation left for one to do, is try them in their own system/home and determine if they make a difference in their own listening experience.

                                            Another rerun:

       That the studies of QM and QED have been revolutionizing virtually every branch of Science, since the early 1900s, has been firmly established.

                                          That's called, "HISTORY"!

https://www.livescience.com/33816-quantum-mechanics-explanation.html

https://www.sciencedaily.com/terms/quantum_mechanics.htm#:~:text=Quantum%20mechanics%20is%20a%20fundamental,quantum%20chemistry%2C%20and%20particle%20physics.

        Not to mention the multitude of modern inventions, that are the results of the same.

https://en.wikipedia.org/wiki/Applications_of_quantum_mechanics#:~:text=Examples%20include%20the%20laser%2C%20the,systems%2C%20 computer%20and%20telecommunication%20devices.

        The evidence is all around us and ONLY the most obtuse, or: willfully ignorant, could possibly ignore it.

                            To deny the above exemplifies the Dunning-Kruger Effect*!

         Were one needing a thesis submission, to a Psychology Undergraduate Office; the local Naysayer Church would make an excellent case study of the above*.

@jhnnrrs Dude. Get a grip. It’s a nasty mess when a flat-earther’s head explodes. It's Haz-Mat time.