Many new electrical facts have been established in the past 100 years, that support audible differences, between various cables, etc.
I agree. Even though, the facts may be not at all what the proponents of hyper-expensive cable offer as explanations for the alleged superior performance of their products.
It does, however, emphasize/demonstrate how Electrical Theory has progressed, since the 1800s:
Yes, a university 101 Quantum Mechanics course usually includes exactly such a discussion. The corresponding theory was mostly built by 1930.
Here we advance to a university Quantum Electrodynamics course level. Yes, photons are considered field carriers of electromagnetic force. The contemporary theory was formulated by early 1960s.
It's an established (measured) fact that an electromagnetic wave's propagation and speed, are dependent on the materials of which the transmission line (cable) are made (ie: Dielectric Constant/permittivity). The better (lower) the Dielectric Constant the better the flow and the longer it takes for that material, to become polarized.
There are no traveling waves in the case of an audio-frequency signal encoded as electric potential applied to a cable.
A crude analogy: take a piece of rope suspended at one end, and start slowly moving its free end. You will observe no traveling waves. Only a gradual movement of the rope as a whole.
Now keep increasing the frequency of periodic movements of the free end. At some point you may reach a characteristic frequency, and observe a wave that appears to be traveling.
One reason anything that comprises an RLC circuit (ie: capacitors, cables, PC boards), takes time to, "form" or, "break/burn-in".*
*Something that makes the Denyin'tologists apoplectic.
https://resources.pcb.cadence.com/blog/2019-dielectric-constant-of-pcb-substrate-
Yes, this is very important, yet once again, for significantly higher frequencies than the ones present in an audio signal.
and (note: frequency figures in EVERY equation and our typical music signal is comprised of a VERY complex mix of information/frequencies, potentially lending to multiple time smears, if not handled correctly):
https://unlcms.unl.edu/cas/physics/tsymbal/teaching/EM-914/section5-Guided_Waves.pdf
On page 4 of this paper, you'll find a criterium for a wave propagation. Non-propagating waves are referred to as "cutoff modes or evanescent modes". For more details in a more accessible format, please see:
Even the most inane (regarding the Sciences) must admit; braiding and twisting wires eliminates/reduces EMI interference.
That, of a necessity, lends credence to various cable geometries.
Yes, shielding from electromagnetic interference is crucial. Even when the frequency of such interference is not in the audible range, it can create intermodulation effects in active amplification components.
A competent audio cable designer would follow official guidelines to ensure the cable rejection of common EMI, to the degree acceptable for a cable class.
Professional-grade cables terminated with XLR connectors would require to pass a higher EMI rejection threshold compared to a home-use audio cable terminated by RCA connectors.
That better dielectrics enhance the propagation of electromagnetic waves (ie: your music signal), lends the same credence to choosing cables with better materials (ie: Polypropylene, Teflon, air, etc).
Since there are no actually propagating waves at the audio frequencies in a commonly used audio cables, this argument doesn't apply. In fact, perhaps surprisingly, a better "cable" could be made of two non-insulated thick wires not touching each other, provided that no significant EMI sources are present in its vicinity.
Of course: anything the Church of Denyin'tology's popes can't fathom, they'll summarily dismiss (uneducated twits that they are).
As I already mentioned, this characterization doesn't apply to me. I'm an educated professional in a relevant field.
I (personally) know of no one that listens to test signals, via their home audio system and (as alluded to above*):
That's a loss for those who don't measure an audio system output on test signals. I lot could be learned from that.
there's MUCH MORE involved when attempting to reproduce the complexity of music in a reverberant environment (ie: various voices instrumental, vocal, their separation/placement and ambient information).
Agreed. But electromagnetic properties of competently designed practical cables have little, if any, influence on that.
Happy listening and (as Richard Feynman would often encourage): NEVER STOP LEARNING!
What would help here is learning about active amplification elements reaction to changes in their temperature. Bipolar transistors, especially, exhibit strong temperature-dependent effects.
A thick cable made of premium materials may, under certain circumstances, serve as an auxiliary heat sink, shifting down the equilibrium working temperature of transistors and other components in an electronic device.
But then again, a similar, or even stronger, effect may be achieved through proper installation and active ventilation of said electronic devices. Buy a 12"-18" electric regulated fan and operate it on a silent/slow setting.
Observe sound quality changes, if any, over 15-30 minutes since the fan was turned on or off. Be aware that specific temperature-related changes in audio devices performance may or may not be preferred by a particular listener.