I had a lengthy conversation with Ruipro and they claim completely different things to what is a common knowledge in this thread. Confusing.
I bought Ruipro certified HDMI 2.1 cable, even thought I completely don't need the 2.1 part (my PJ is only partially meeting 2.0b) because it is certified and if to believe them and the standardisation process it's power draw has been optimised and minimised to meet HDMI specification.
Ruipro said their new certified cables have the lowest power requirements of any of their cables and even that they come with injector supplied as part of the package they don't recommend using it until faced with problems.
They also said that injector can be used on either side of the cable and that the recommendation is to actually use it on PJ side...
They also explained that using injector when not needed (which is a vast majority of cases, according to them), the injector will not be providing any power but just degrading the signal by being there as another link in the chain.
So there you go ... We spoke for about an hour, about different scenarios, failures etc.
They also claimed their cables run correct voltage. I would like to see the article that measured differently and show it to them to see what would be their explanation.
If somebody could link it that would be great.
Finally they said that occasionally injector might be needed AVR side when there is a multitude of devices connected to it and it's bus is running out of juice.
But more commonly PJs are having issues with eARC with optical cables (so everything is working as advertised but eARC) in which case, injector PJ side, usually resolves the problem (which I am guessing might be down to optical cable loading PJ bus to that extent that eARC so LAN module has not enough power to correctly run eARC protocol and functions).
As usual the truth most likely lies somewhere in between those two camps.
I have few days to do more research and decide which way I will be using my cable, but as it is certified I think I might give it a shot without injector? Or am I brave here or just plain stupid?