[higgsfield]

A lot of people have invested a lot (not just money) in their opinions.

Digital signals can however degrade to the extent that bit errors, beyond the scope of error-correction can be introduced. Furthermore, jitter can make clock recovery imprecise, which can also lead to errors.

However, in these extreme cases, failures will still tend to be of the relatively catastrophic nature.

It is not possible to explain how better pictures or sound, can be attained by a cable upgrade. People can be convinced of many things though so and any amount of anecdotal evidence to the contrary must be dismissed as irrelevant. Unless, that is, I am missing something fundamental about the design of ICs and interfaces. I hope not - as that's part of my job.

Anyway, I hate to sound arrogant - but until someone successfully shows how a cable can possibly affect the clock and data recovery process in any way that would manifest itself as picture (or sound quality), the inescapable conclusion is that it's impossible.