Yes, I am fully aware that to avoid issues with frequency response you want the outputting device to be ~10x less than input device, which is why most amps are 10,000 and as you stated an output device would be 1000 at the higher points.
Well, true for audio, where matching is not required. For RF systems, optimal power transfer and signal integrity happens when the source, cable, and load are all the same impedance. For example, your antenna or cable box, cable, and TV receiver are all ideally 75-ohm characteristic impedance. That is a high-frequency impedance, not audio. For analog audio signals, while the cable still has 75-ohm impedance (*), it just does not matter as you are not working in a matched environment and the frequencies are so low as to be DC to the cable.
"These cables are designed to carry GHz RF signals" so is that what you are saying is coming out of the dac? the dac has no limit to frequency output? I think from amirs video's, which I did not really comprehend is higher 192khz is actually playing out to 192khz, I did not actually correspond those sample rate to what the dac is putting out. Didn't tie that together until it was pointed out. I do not want to talk about this subject, but at 192 khz you are able to hear about half of that. 44.1khz you get about 22k out which covers the entire band. Lets not talk about this though, this is just a light bulb moment.
No, the cable itself is usually an RF cable, because it is cheap and widely available. It is often the same cable (impedance, though larger in diameter) used by cable companies to send the signal many miles, and used for both video and some digital signals that are much higher bandwidth than analog audio. The cable will support signals to about a GHz. The DAC is putting out analog audio, with a bandwidth usually about half the sampling rate (look up Nyquist). So a 44.1 kS/s DAC has a top analog output around 22 kHz, and 192 kS/s tops out around 96 kHz. Coax is used because it is cheap, shield against noise, and easy to work with.
Yes, logically I did tie the conductor size to different electrical characteristics. With the tests on audioholics regarding speaker cables that's the pattern I saw. Even with two cables of equal gauge the proper geometry cable was having far superior performance in some aspects, but reactance is acting up. I mean on longer speaker cables this maybe something to consider, not a huge deal on interconnects especially for at home use.
Speaker cables handle much higher power and work at much lower impedances. Audio is still essentially "DC" so the only thing that really matters the vast majority of the time is the DC resistance, not the characteristic impedance. Coax is usually specified in terms of characteristic impedance for RF signals, but specs listed usually include R, L, and C per unit length. Unless you have hundreds of feet or more of cable the only time any of that matters for an interconnect is for the cable connection from a phono cartridge to the phono preamp, since most (MM) cartridges drive a very high-impedance load (e.g. 47 k-ohms) and are sensitive to the load capacitance. Coax cables run around 30 pF/foot, so you may have to change the preamp's load setting if you have a long cable.
I think probably to sum up everything, is that even the most expensive interconnect cable with greatest measurements is not going to provide better sound but rather not create any limitations or degradation to the frequency response.
IME the better interconnect cables use better connectors and have overall better construction, like welded connections and 100% shield vs. the 90% or so of standard standard coax (which is still plenty good -- that is what I have in my system). As for measurements, I would bet the vast majority measure about the same independent of price. It is hard to imagine a case wherein the cable would limit the frequency response in a home installation.
On a sidenote
I am very new to audio, just started in september of 2020, so I am just over a year and half in. Sometimes I get these random thoughts that I would like to learn about or better understand. Even after watching and investigating so much, and now even further justified by Amir and Audioholics. Just a very general knowledge I have in physics has told me that I am not going to invest a foolish amount of money into cables, it doesn't really make sense at all.
Learning is good, common sense is even better. Actually hard to have one without the other.
I just use some Monolith RCA cables and some mogami XLR's which measurement wise do have some good noise rejection with testing to prove it. Honestly see no issues there and compared to my old cables I do see that it[RCAs] does "sound" better which maybe just placebo. The only other thing that makes me wonder, and I do not wish to discuss it as we have no way of proving it, is if different metals have any sound characteristics as most people say. Measurement wise I do not think there will be a way to tell, and I am not sure if different metals will have different electrical characteristics which is what people are hearing. Even then that one is strange to me because you have a cable lets say is all silver, and then you put it on connectors which are silver plated and brass under or copper, and you would have to assume that's almost bottlenecking any performance you would actually gain.
I don't know anything about Monolith RCAs. Mogami is good cable, along with Canare and some other brands I have used over the years in both professional installations and at home. I think different metals having different sound is perception bias. Yes, different metals have different characteristics, easily measured in a lab, but for audio those differences are irrelevant assuming common materials like copper, silver, gold, nickel, etc. I have noticed a consistent trend for silver to sound "bright" and copper "warm" but personally think people are hearing with their eyes.
The only final factor which comes into play crystal structure and the crap they have in marketing. I honestly cant even truly understand that and my current research which started this topic shows that a cable with 99.99999 cable is actually measuring worse than it's 99.99 counter-part and costs double. So not seeing any real influence there. Also considered conductor size on this matter, and the better measuring cable does have twice as much conductor, however the rest of the performance is almost 3 times as bad so the purity of the conductor plays no role.
Crystal structure is a big deal for some cases but not audio. A cable for a 100+ GHz test system is critical and has special needs. A cable for a 20 kHz (or 100 kHz) audio system, not so much. Ditto the dielectric used (the material between center conductor and outer shield); it matters very much in some applications requiring very wide bandwidth or ultra-low noise, for applications many orders of magnitude grater than required for audio. Ironically, some of the dielectrics highly-regarded by audio marketeers, are worse for noise than cheaper, more common dielectrics. It does not matter because the noise is many orders of magnitude below what we can hear (and is difficult to measure even with fancy test equipment).
There have been endless marketing adverts over the years showing minute differences blown up on a graph to indicate vast superiority that is just not audible. A certain cable manufacturer showed a plot with their cable having much greater bandwidth and much lower loss than a competing "no-name" cable. The catch was the plot scales were not shown, and later found to be fractions of a dB and MHz in frequency. So the differences were real, and measurable, but ridiculously beyond audibility.
And so it goes - Don
(*) Characteristic impedance actually gets a little fuzzy at very low (and very high) frequencies, but for our purposes it does not matter.
Edit: Many years ago there was a big debate about how RF effects in speaker cables mattered, and I wrote a little blurb about it. I think it was transported to ASR, check the articles linked in my signature. The bottom line is that you can do the analysis, but for homes the effects die out in ns or so IIRC, far, far, far! faster than any speaker can respond or we can hear them.