This is good stuff - preaching mostly to ether here but good still. These are things the mods should sticky or add to a wiki.
I’m an electrical engineer (BSEE and BSCpE) with a focus in power, I know this stuff “pretty well”. Prior to becoming an engineer I sold high-end audio for years. I was the snake oil salesman but only because I actually believed what I was being told. While in school I ran tests all the time in home audio gear. Needless to say, I run Home Depot extension cords for my speaker wire (wrapped in wire loom to appease the wife). For cables, I run a mishmash of moderately priced ones - $50/six feet range.
On one system I do run a 2-channel Carver with XLR. I ran the same with an RCA adapter and I tried to hear the difference but couldn’t. I then put it through an o’scope and never saw anything (arguable very difficult to see but I tried - and this was an input vs output comparison too). Never a bad idea to run XLR but not needed in my setup and likely not for your average audiophile.
At the home audio level, spending more is rarely ever justified. In your world, wether in a studio or stage, this stuff becomes SUPER important, as you know, but home audio it becomes snake oil really quickly.
I can tell you as an electrical engineer with a focus in power (this is what I studied and did for a living), there’s absolutely zero scientific reason that non-defective, inexpensive cables/wires would sound different than some more expensive cables/wires in this setup. Zero.
My bet is that they altered a setting, or maybe they “fixed” a connection or something else that a company that makes snake oil products would do.
Here’s my funny story: Prior to becoming an electrical engineer, I sold high-end home and car audio (McIntosh, B&O, ML, etc.) and I sold thousand dollar cables and wires to “match” these systems; I bought the snake oil and it was very profitable. Fast forward and years later while in college I chose power (transmission lines, signals, etc) as my focus and one of my professors is a HUGE audiophile - guy lives for Russian & Soviet-era tubes, kinda audiophile. He and I geek out on testing audio cables and wires for years - not so much wires since that’s pretty black/white but cables at least have the potential to accept interference, and then more importantly, pass that interference on to be amplified.
I run Home Depot extension cords for speaker wire and my cables are around the $50/6-feet range. I do have some XLRs running with a Carver set up but after running multiple tests with my ears and then finally with an o’scope, there was zero difference found.
Point is, beware of the snake oil salesman and their products. Unless you have a truly unique situation, you shouldn’t ever have to pay much for perfect cables/wires.