Perhaps there is no current viable device that will measure our sonic preference? I mean all we have is Ohms law. If you're hearing and your system is transparent enough, most people will be able to detect the differences. Why such a denier? Try it.
I might.
OH, and: it takes some time for the dielectric to form, take a charge, polarize, or however one chooses to define the process, when a dielectric is subjected to electromagnetic waves, which affects the Poynting vectors, measurably/predictably.
The lower the material’s dielectric constant: the longer that takes.
At 60Hz, that is a huge time.
I can abide that speaker cable playing the 1kHz or 10-20 kHz can do all that, but 60Hz is very low.
Maybe being on 50Hz makes it less of a problem?