The impossibility of sound quality difference whatever the medium

[f1eng]

Don't forget the placebo effect.
The placebo effect is real and works.
In the case of curing a real illness only some illnesses can be cured by placebo cures in many, but not all, individuals. Surprisingly (to me anyway) this is the case even when the subject knows they are receiving a placebo. It is a sufficiently well known phenomenon that in some countries placebos are a permitted medicine for some ailments.

If the subject believes the placebo to be expensive it is more effective.

My personal opinion is that whilst many people hear an improvement due to cables there is absolutely no reason why a real one should actually exist between adequate cables and the difference heard is real to the listener but is simply a manifestation of the placebo effect.

To rule out a placebo effect there are blind tests.

Indeed there are, and I have yet to hear about a single valid blind test in which cable differences were heard and seen dozens, maybe over 100 over the last 30 years, where the apparent sound differences were unable to be confirmed in a controlled blind test.

I have been a practicing engineer for 45 years, starting out in noise and vibration research, with racing car engineering as a paid part timer but eventually designing and running mainly formula 1 cars as a full time job.
During the whole of my career I never found a phenomenon which was not explained by physics, even if it was difficult to analyse initially.
I do not believe in magic, and all the sales BS about jitter, insulation dielectric, conductor material and so forth are demonstrably simple marketing bollox. At audio frequencies cables are trivial bits of engineering and as long as the LCR is appropriate and the connections well engineered they will all do the same audio job, digital, interconnect or speaker cable.

The whole hifi cable difference issue can only be satisfactorily scientifically explained by the placebo effect, no other explanation that I have heard, and there have been lots, holds water.
The placebo effect allows differences to be perceived where there are none and few things fit the placebo effect explanation more neatly than cable sound differences.

I absolutely believe that some people hear differences between cables and are happy to spend their money on expensive ones.
I have made the mistake myself in the past and still use some of the expensive cables I bought when I thought I could hear the difference since I own them already but my latest speaker cables we <£20 and I use standard cat 6 ethernet and standard optical leads.