Seems like every year or so a new debate begins, concerning cable mythology (really, it is the most appropriate word). Maybe we can shed some light on the debate, by discussing what science ... metallurgy, electrical engineering, etc ... tells us about cables.
I'll start with an anecdote ... "my experience" with cables, if you will. It was an old trick among audio salesman ... even twenty ot thrity years ago ... to swap out RCA cables, and demonstrate what an incredible difference was heard. Even the most tin-eared idiots could hear a difference! Putting aside, for the moment, the strong power of suggestion, lack of variable control, lack of accounting for presence/absence of human memory effects, and all those things that tend to render isolated, uncontrolled subjective observation meaningless ... could a difference actually be heard? The answer was YES ... but it had nothing to do with the cables, per se. The reason was because simply removing an RCA cable and plugging-in a new one would scrape the oxidation and corrosion from the metal at the surface contact, improving the electrical connection. In fact, unplugging a cable and plugging back in the very same cable could create an audible ... and measurable ... difference
Let's start by stating the obvious : at both the line-level and speaker-level points in the audio reproduction chain, the signal is electrical in nature ... rather than mechanical or acoustical. I suspect most (perhaps not all) would agree with this point. So the question naturally arises ... what electrical properties of the cable matter?
The answer is remarkably simple. The cable is an electrical network, and it's operating with signals whose electrical wavelength is much, much longer than the cable itself. Therefore, what matters electrically are the parameters in the classic "lumped model" : namely, the cable's Resistance (R), Inductance (L) and Capacitance (C). We can completely discount all transmission line effects ... including standing waves, reflection coefficients, and termination impedance matching (excepting, of course, digital audio transmission ... when the signal is digital, it's bandwidth is orders-of-magnitude higher than analog audio).
How the RLC parameters of the cable effect the signal transmission will depend on the source and load impedance ... in other words, what's driving the cable, and what's on the other end. Knowing these impedances will allow us to measure, or predict, any alteration in the audio band frequency response ... aka magnitude and phase versus frequency ... that a given cable may generate. Linear system theory is a well-established science ... not open to opinion or subjective experience.
Any general conclusions? Sure ... for example, it takes a real effort to significantly impact frequency response at the RCA/line-level, because the load resistance is so high compared to the series elements of R and L. You may, however, want to pay attention to the shunt capcitance in interconnect cables ... it's possible that the capacitance may cause some roll-off in the treble, with a long cable (meaning, high capacitance) and high-ish source impedance. Similarly, you might want to pay attention to the series elements of R and L at speaker-level cables, particulary when driving low impedance loads (like low impedance subs, or highly-capacitive electrostat panels).
Anything else matter about cables? YES ... contact metallurgy, as mentioned. Not only can certain metals oxidize and corrode (impacting that parameter R), but dis-similar metals in a pressure contact can create galvanic effects that demonstrate very measurable ... and potentially audible ... effects. Furthermore, we must include the noise-shielding properties of the cable. How significant? Depends, of course, on how noisy the environment is
What's the bottom line? Let's do some make-pretend Q&A:
Q: Do all cables sound the same?
A: OF COURSE NOT ... but the question is meaningless. A rusty, 30 gauge cable that's 40 feet long will obviously sound different when driving 800 watts to your sub, compared to a short, clean 12 gauge cable.
Q: OK ... so what causes cables to sound different?
A: The only parameters that could matter are RLC, contact metallurgy and noise shielding. The significance of each, depends on the exact environment and application.
Q: What about hyperlitz geometries and specific metal elements?
A: If they don't impact RLC and frequency response over 20kHz, they won't impact the sound ... simply because they can't. If the electrical signal is not altered over a 20kHz bandwidth, the sound coming out of your speakers won't be altered either.
Q: What about the "network boxes" on some super-megabuck cables?
A: Of course they can alter the sound, if they are providing a change to the frequency response (magnitude, phase) of the network operating on 20kHz electrical signals. In other words ... if they are providing some degree of equalization, they can change the "sound". Linear system theory tells us that there is simply no other way to alter the signal, or thereby the "sound" of the cable.
Q. Do all cables ... THAT MEASURE THE SAME ... sound the same?
A. No known reason to believe otherwise If you wish to disprove the hypothesis, though, you must of course establish an experiment where all other possible variables are eliminated.