... If it can't be measured, it sure as hell won't be audible outside of the imagination. All of these things are completely understood. ...
This is the only part with which I disagree. I'm old enough to have learned that we underestimate our ignorance all the time, every day. For one thing, we measure things that do in fact correlate with what we hear, such as distortion, and then SETs force us to acknowledge that we have over-estimated the importance of THD measurements. Symmetrically it is highly likely - almost certain, in fact - that there are measurements we either have not yet learned to make, or of which we seriously underestimate the importance.
The classic example for me is break-in of capacitors and transformers. I am not aware of any measurements that correlate, but I have heard the effect so consistently, in so many cases where I was not aware of the history, that I cannot deny the effect.
We, and other species, have many senses which are more sensitive than we can measure. Why else would anyone use dope-sniffing, or bomb-sniffing, dogs if we could simply measure the trace aromas?
My career experience is as an engineer, so I respect the consensus of perception when I am unable to make a measurement to trump it. Sure, often enough the consensus is a form of mass hypnotism and one must always be prepared to abandon it when something more reliable appears. But until then, the closest thing to reliable always wins, no matter how far it may be from satisfactory. In this I differ from my training (I was originally a mathematician). I am however very cautious about extrapolating beyond the realm of actual, experience-based consensus!
For what it's worth, I have heard the effects of different wires and interconnects but my personal experience base is too small for me to have a solid opinion. I rely on the forums for a wider range of experience (and on those whose ears I trust) but I remain deeply suspicious. :^)