For Your Edification and Enjoyment re "Burn In", etc.

Denverfred,

if you want empirical, Abbey Road Studios uses Van Damme cables throughout, 2.5km of it, at £4 per metre. If spending more than that was necessary, I think they would. Good enough for them, is good enough for me. I use it throughout too. But not 2.5km !

Douglas - an excellent article, congratulations. How refreshing to read sensible, objective, honest, thorough, grounded opinion, written well. 
Do keep reposting it here, won’t you, as needs be...

In which case Doug has it right. The reader inferred something from Doug’s post. (I doubt Doug implied he had nothing more to offer than the average hobbyist, so the reader must have inferred that.  Or so Doug implies, anyway). 
You are implying Doug doesn’t know the difference between infer and imply. Doug can infer from your post that he does, and you don’t. 

Null test - you play sound 1, then sound 2, and subtract one from the other. If you end up with zero the sounds are the same. 
Example here shows that all cables (let alone new vs burned in versions of the same cable) are the same: https://audiofi.net/2019/01/audio-engineer-claims-his-null-tester-settles-the-debate-on-wires/

Doug - (or anyone) would you do an experiment?  
Run “burned in” cable to one speaker, and a brand new version of the exact same cable to the other.  Invert the phase of one channel. 
Play a track in mono. In theory, shouldn’t there be silence?

if there isn’t silence, an explanation could be that the sounds from each speaker are different and therefore don’t cancel, therefore the cable differences are real. 
But, there are other explanations to discount. Maybe the reflection in the room are not perfectly symmetrical. So we can discount that by putting new cables to both speakers (or similarly burned in ones). Play mono out of phase again, and do we get silence now?

If we do get silence, then there is evidence that the lack of silence before was due to differences in the cables. 
If we don’t get silence, then we know any differences actually due to cables will need to be unpicked from differences due to the room. 
The noise in the room in the two scenarios can be measured (and listened to) and compared. We will then get an estimate of the relative effect of room reflection asymmetry as compared to cable asymmetry. 
Thoughts?  Mine are that in any home listening environment, the room reflection effect (and tiny variations in speaker build, etc) will completely dwarf any differences arising from cable burn in.   It would be nice to know though. 
First issue - am I right about inverting one channel of a mono sound resulting in noise cancellation?

Mahgister - I can’t think of anyone who needs to accept and use blind testing or null testing more than you.
You have all the characteristics of an innovator - an inquiring mind, a desire for improvement, and a willingness to experiment.
But you have no proof. The null tester in the link I posted has proof - scientific and engineering proof - that the $3 and $1000 interconnects passed the audio in exactly the same way.
You have no proof that painting that cable, or lifting it up on blocks, or burning it in, or switching it with another makes any difference at all. You only have claims.