Harley quote

Regarding two aftermarket power cables: "These differences in the shapes of the musical waveforms are far too small to see or measure with even the most sophisticated technology, yet we as listeners not only routinely discriminate such differences, we sometimes find musical meaning in these differences."

 Nonsense. Just because people claim to "routinely discriminate" differences doesn't mean it's true or they're right. Apparently many have witnessed UFOs but that doesn't mean they actually saw extraterrestrial visitors, does it? Some have seen/heard a deity speaking to them "routinely"; does that imply that they are surely communing with an unseen/unmeasurable spiritual force(s)? Can we not put a little more effort into confirmatory reality-testing first when "the most sophisticated technology" can find nothing in 2020? (Of course, speaker cables can measure differently as per here, here, even if not necessarily audible in many cases by the time we connect amp to speaker.)

My perspective on cables begins with the hard won recognition (Read putting thousands of dollars into cables temporarily, comparison of sets, reviews of sets of cables, and constant system building with those sets.) that cable manufacturers indeed know quite a bit about signal and power transmission. From that stems the suggestion that it may be beneficial if audiophiles would humble themselves to take the cable makers' suggestion to use an entire set. 

What is accomplished of value in terms of assessing with intent to drive a system toward a desired sound by mixing cables? Nothing. No baseline, no means of assessment of what any particular cable is doing. It's pretending to act like you know what you're doing. Then, consider the irony that the cable mixer rails against the manufacturers as though they don't know what they are doing! This is the epitome of hubris. 

My point is simply that, quite apart from ABX, which I have done and successfully selected the proper cables with far greater than 50% accuracy, as outlined in my review of the Audio by Van Alstine ABX Comparator), if one wishes to lay to rest the issue of perception of cable changes, swapping out one or two is not the ideal. Comparison of sets is the ideal, which imo most do not pursue due to the cost and work involved. That's understandable, but it's not supportable to suggest that mixing cables is advantageous. 

One could, theoretically compare two discrete sets of mixed cables, and that might ( I would suspect with less certainty) reveal significant enough differences between the two mixed sets to convince in regards to efficacy of cables. But, that is of little advantage to the audiophile, who would gain no understanding of the contribution of any of the cables. The far more sensible option would be to compare entire sets, from which a baseline sound is found, then other cables can be swapped in purposefully. I have done this with many sets of cables to the degree that I know the innate sonic character of particular sets of cables, and can select from particular cables to tune systems. How is that supposed to be done with mixed cables, when you have no understanding of the sound of the cables? 

Much of what I see happening in this hobby is considered proper form, but I see it as thoughtless consumerism. How else do you explain someone buying a cable in isolation from the set and thinking they  have any idea of what it will do? 

In order to properly assess cables and properly present them as having audible changes regardless of what measurements show, I would seek the maximum impact, not the minimum. Imo, that begins with putting some trust in at least a handful of cable makers who you regard as legit, design savvy, etc., then working with a full set to gain a baseline that is not fluid, and finally rotating out sets to hear fundamental differences. 

This has been my MO for reviewing as well, but with the addition that I build many systems in assessment, as opposed to few systems. 

I believe that were these principles to be followed, the debate could be resolved with more finality than the machinations that happen incessantly. 
Finding the right cord or cords for each piece of gear can make a bigger difference somtime than buying or upgrading it can be a much easier and less expensive route to take especially with a good dealer involved.
It is not hubris that I have forgot more about electrical engineering and physics than most of these cable charlatans know it's just fact based on their own writings.

Far greater than 50%? Is that 51%, 60%? because if the claimed substantial change is there it should be much > 75% not 50%. Were the levels matched to 0.1db,? How?

This concept of full loom to me is just silly and ignores the very real and substantial impact of component interaction as the only thing that will generate real sonic differences.

I am all for blind testing and I read the designer's (I assume) response under the review of above mentioned ABX Comparator...

"First of all, the capacitors, integrated circuits, diodes and resistors are not in the signal path at all."

What is the use for so much electronics in what is supposed to be an inert device?

Audio by Van Alstine ABX Comparator Review, Part 1: Audio Store & Wiring - Page 2 of 2 - Dagogo
Audio2sound, more like 80-90%. Read the article.