Bigtwin, you already tried to mess up the tread twice. How about letting others answer the question for the OP.
For me, system noisy one day and quiet on others. Especially with tubes.
Having just went through a power upgrade, I can provide my experience. I went from an old electrical panel and one 15amp line to having a new panel and three dedicated 20amp 12gauge Romex lines, good Siemens breakers, each placed as far away as possible, better grounding, and run to quality Audioquest outlets. I kept it as simple as possible after doing a lot of research prior.
My system didn't sound bad before, but it went up several levels after the upgrade. Noise floor dropped significantly, bass strength and definition improved, more detail comes through, and the whole system sounds more 'effortless'. It made a bigger difference than many components I've added and was significantly cheaper.
Power cable influences on equipment has to do with a) less contact resistance b) less rfi and emi pick-up, and transfer to the component c) less cross-contamination from components on nearby other components and cables d) less voltage drop e) less (lower) leakage currents and parasitic capacitance between components.f) quicker rise times/faster current draw.
But, if the incoming electricity is dirty the effect will be reduced offcourse,
Sometimes changing one power cable can have an effect on other equipment in your system.You only hear the endresult. A lot of people have heard the change a good power cable can bring to your system. Who I am to judge? If you don't hear it, be happy and listen to some good music.
Love to hear other peoples experiences. 'Facts', 'Engineering' and 'Measurments'. can be discussed in Tech Talk.
Nobody is asking you to be onboard. If you are happy with your system then why spend more money? If you just want to accuse others of being fools, then I guess that nothing can be done.
Well designed power supplies are important, but I have to believe that at the level most of us purchase, that this is a given.
You want to understand equipment and I want to listen to music. So, my approach was to rely upon a few people to assemble my system. One sang the praise of Shunyata power and cables. I believe that it takes a major investment in conditioners/cables to be able to verify, or refute the sonic improvements of this equipment. If you cut corners, then how can you be sure that you have tested the technology. Given this as my approach, I ultimately purchased Shunyata’s top conditioner and cables with the understanding that I could return everything for a full refund. Even better, I was able to use the vendor’s shipping department on items, such as cable and a phono preamp that I didn’t like and they charged me little for shipping. So, I read all of the Shunyata marketing information, had a recommendation from someone I trusted and then listened to the results. Again, I purchase based upon results, but those results are in the real world and not just between my ears.