Are manufacturer AC cables good enough?

Again;  The hypothesis is (whatever the particular wire, tweak, etc); that a change (good or bad) can be heard.        The naysayers propose (perhaps, project), that, "audiophiles" are too ignorant, inept or deaf, to make a change, in their systems, listen to it and determine if it (whatever it is) makes enough difference, to them, to purchase (a simple experiment).       Without a knowledge of the root, which births such hubris, one could almost get offended.      ie (the root):     https://www.britannica.com/science/Dunning-Kruger-effect

Well most of universe is a very very far distance away making measurement a bit difficult unlike our audio systems.  We don't know if our gravity equations are wrong, or our measurement of matter is wrong.

We used to think that E = 1/2 m * v ^2, was totally accurate, and for most practical purposes, it is more than accurate enough. Audiophiles or at least audiophile marketers attempt to create reasons that would actual be pretty easy to measure within the limits of any necessary accuracy, whether we understand "everything" or not, and then make excuses about why they can't be measured and attribute that to this global "well we don't understand everything".  They don't even try to reconcile their claims with what we do know, let alone the things they claim we do not.

Never said gravity couldn't be explained.    The amount of gravity, throughout this universe, has not yet been explained.    

The naysayers propose (perhaps, project), that, "audiophiles" are too ignorant, inept or deaf, to make a change, in their systems, listen to it and determine if it (whatever it is) makes enough difference, to them, to purchase (a simple experiment).

I am the one who is accused of being inept, ignorant and deaf not to mention a troll etc.. for simply pointing out "audiophiles" are human and subject to the same biases as all of us , including me. Acknowledging this it only makes sense to try and negate these biases as much as possible when making claims of HUGE improvements in the sonic abilities of amplifiers etc..power cords, which are fairly well understood passive electrical devices.

Dude! E = Mc^2 is always true. Mass and energy equivalence and all that jazz. Wake up and smell the photons. 💡 

heaudio123
Well most of universe is a very very far distance away making measurement a bit difficult unlike our audio systems. We don’t know if our gravity equations are wrong, or our measurement of matter is wrong.

>>>>Well, distance is all relative. You’re just used to very short distances. By the way we have no problem measuring anything universe. Distance is not really an issue. We can measure the mass and spin of a black hole millions of light years away, no problem. Or the source of radio signals from space as they’re doing right now. You know, like in the movie Contact. In fact, now that I think about it they can measure almost exactly the distance to the edge of the universe. Hel-loo! Now, audio is a different story since measurements oft don’t comport with listening experience. That’s the way it goes sometimes.