Electricity is the fuel to your system. You even can describe it as the oxygene to all your parts in yoyr system. It makes a huge difference. But a powercable is only a part in the whole system.
First you need a separate audio group for the electricity. What kind of conditioner do you use?
The things most people have no idea about are: SMOG, HIGH FREQENY NOISE AND MAGNETISM.
And mann they have a huge negative influence on your system.
I see you use a Marantz for surround. We did recently did test a 8801 pre map. And mannnn it was extremely poor in all parts.
Marantz is for 100% a 2D product. No one can change that. The other part in which Marantz is very poor is the quality of their videoscaler inside.
We use the best and most expensive Calman 2017 software and the new 2017 tools to calibrate screens and beamers.
Even the LG Oled 2017 topmodels gave a very poor result even with the 8801. It lacked 3D image, the colours were not that natural. And the details were rather poor as well. The best AQ HDMI cables were not able to solve it.
When you take a look inside the Marantz products you see the cheap parts. This proofs how limited they are. The company who does the technical support of Marantz in my country told me how poor the parts are they use.
Onkyo in 2017 do it even the same way. it shows how low quality you get for the money you want to spend. The reviews are often paid. So Ricred what would you like to hear?
The truth or the thing you would like to hear?