How to measure Cable Sonic Differences

Garth Powell speaks of (specially??) distorted Baxandall subtraction technique  (see schematics and description here https://www.backtomusic.ru/audio-engineering/theory/science-and-subjectivism). To get a correct result using the subtraction testing it should be done live, then after proper calibration there wont be any potentially audible difference even if you test the whole amp, not just cables.

IMO the guy is just looking for a dubious ways to explain the sound difference of cables with a help of conventional physics and doing it on a quite a low level.

You can say what you want,
I have no idea what Garth is doing, but the results are amazing.
Every one of his new cables/power conditioner has bettered my system.
Bob

My comment was not about the quality of his cables, but about how he explains their sound. Nothing more.
He probably makes good cables, since people buy them. I can't say anything about it.