The opinion on this forum is that there is no need to upgrade your standard HDMI cables
This is an interesting one. HDMI is a digital interface which uses parity correction. Looking at the situation from a purely technical point of view, digital is digital (just a bunch of 1’s and 0’s) and parity takes care of any losses. Like some types of digital audio interface, there may be some issues with jitter (which is about timing), but I wouldn’t get too absorbed with the hype. Let your eyes and ears be the judge.
There are a lot of companies making high quality cables and when you enter the world of analogue HiFi, these really do matter. There is an element of “perceived” rather than real benefit about all of this, but I have heard significant improvements when switching from one cable to another. Unfortunately, the cables that bring your systen to life always tend to cost vastly more than run of the mill stuff – what a surprize! Finding the middle ground is the challenge (and it is a challenge).
Some cable manufacturers like to talk technical, but i reckon a lot of it is speculative waffle as there is no formulae for matching cables, or specification that you can use to make comparisons.
In the end, cables are part of the chain and each component of the system interacts with the other. Measuring reactance and capacitance is impossible as everyone has different kit. When you change cables, you change resonant frequencies across the spectrum and this simply can’t be measured. It’s all about trial and error which is tough because getting a mix of different cables to tryout on your own system at the same time is pretty well impossible.
Back to digital: don’t buy the cheapest cables, but don’t spend a fortune. The purveyors of esoteric bits of string will have you thinking your life depends on spending vast sums on their blinged up offerings. My advice is don’t be taken in by it all. £20-30 is more than enough to spend on a decent HDMI lead.