Power cable from wall socket to power strip

A simple experiment to understand why any external modification or perturbation or modification around an electrical field may matter and in some cases be audible as a kind of filters:

Put a 200 grams piece of quartz on your amplifier, then try with a piece of shungite of the same size... Go from one to the other and listen the difference ; it will be a slight degradation or an improvement , if it is neither of the two try and put them together,...

if your amplifier is on the warm side of thing , the quartz may help it..

If your amplifier is on the cold side the shungite may help it...

If your amp is more balanced the two together may also did something helpful...

In any case the goal is to hear a "change" for the worst or the better and then you will know how the world is not as described in your manuals ...

A varied mix of some minerals do marvel for my Sansui alpha who sound as a tube amplifier  to my ears : more fluid and no trace of dryness or shrill or anything making it a S.S. design ... the sound is meatier and i modify it at will... It is like using different cables to my ears...Usually i keep my recipe without changing it because there is more no need to balance it further ...

No sarcasms by empty head will be  needed when someone  dare to suggest a simple experiment a 4 years old can do... 😊

«How about a piece of quartz on my front head as a king ? » Groucho Marx 🤓

«Sound need a medium , the air, but sound is not the medium nor the mere waves in it; sound is a real event from the vibrating sound sources or near two sound sources with qualities, localization and duration; sounds are no more illusion than the rainbow, they reflect our own grasp of the sound source and the sound source effect on us» Anonymus philosopher

I start at the source and only use energy from very clean coal.  Diamonds are best but hard to source.  Then focus on cables from plant to substation. 

That provides an airy soundstage.

If you believe a power cable makes a difference, and you believe you hear a difference, then be happy.  I will not tell you what you can or can't hear. I am neither that arrogant nor disrespectable :)

Now as both a subjective audiophile and an engineer:

Yes, they can bleed 60 Hz and harmonics into poorly shielded signal cables. 

Yes, many cheap cords are not even twisted inside to minimize emissions.

Yes they can pick up RF

Yes, I have found cheep cables that were not even welded to the prongs, Just held in place by the overmould! YIKES!

As with any cable, the shorter the better. The appropriate gauge, the better. Twisted the better. Separation from signals the better. 

BUT, OK, several hundred feet of ALUMINUM entrance wire, bi-metallic contacts in the breaker, hundred feet of the cheapest copper you can find in your wall, that "magic cord" and then going into an alloy fuse, tin plated fuse holder and into several hundred more feet of cheap copper in the transformer or whatever they do to it in a switching supply, the ultimate RF generator.   So, is that where you want to spend your money?    I spent mine on some replacement ends so I could shorten and tidy up the cables.  I also have a Emotiva DC blocker as I DO get transformer hum depending on how many LED lights, dimmers and DC fans are running.  Transformers are the very best RF filter there is. I love linear supplies. 

Some even suggest "audiophile" outlets.  Well, there are three actually different outlets.  The 49 cent "contractor" ones with back-stab. Total garbage, swap them all out.   Then the mid grade  $1.95 with much stiffer holding power and a little heavier, followed by the $4 "commercial" grade. What my house if full of.  Snug fit. Good contacts. Don't fatigue. These can also get "medical" separated ground or "data center" which as far as I can tell, differ in the orange or green dot only. 

Your choice.  The only risk is some esoteric "audio" cables are not UL/CSA certified so you are on your own to know if they are safe as far as not starting a fire. 

@simna 

 How can the power cable from the wall outlet to a power conditioner have any importance?
The power has traveled through miles of ”ordinary cable” to my wall outlet, so how can this last bit to the power conditioner, that is supposed to clean the dirty power, have any impact on the sound?

       Did you bother to read anything I posted?

       Bother to LOOK into any of the SCIENCE involved/mentioned?

    Virtually every modern convenience, computer, electronic medical, listening or communication device you've been enjoying, invented since the late 1900's, resulted from the study of just those (mentioned in my posts) phenomena.

        While what I've posted are my postulations (far as PCs); they are based on some VERY SOLID SCIENCE (Physics/QED).

                                                    references:

https://en.wikipedia.org/wiki/Applications_of_quantum_mechanics#:~:text=Examples%20include%20lasers%2C%20electron%20microscopes,systems%2C%20computer%20and%20telecommunication%20devices.

https://www.forbes.com/sites/chadorzel/2015/08/13/what-has-quantum-mechanics-ever-done-for-us/?sh=37c459944046

https://uwaterloo.ca/institute-for-quantum-computing/quantum-101/quantum-applications-today

https://www.smithsonianmag.com/science-nature/five-practical-uses-spooky-quantum-mechanics-180953494/

                                              Happy Listening!