Sound of cables breaking in?

These days one can use a USB stick with some tunes on it, even on an old DVD player (with USB input)..and burn that cable in, via playing music signals from the USB/DVD player, into a unused input on your given rig. Let that sit for days at a time, and then the burn in in is done..

So one does not have to waste precious hours on cartridges, or tubes or whatnot. One does not even have to hear it break in. Let the USB/DVD 'burn in rig' play 24/7 for 3-4-5 days..and then you are done.

One can also use specific burn in signals, like pink noise, left running on repeat, off that USB stick.

So, equipment required: One of the ubiquitous USB sticks, an old DVD player with USB input, an input L-R pair on your rig, and the mental wherewithal to get the tunes or burn in signals on the USB stick and make it (the DVD player) run on repeat.

yep, I have experienced all of the above.  Good out of the box, then they got shouty, loud, hard, grainy, or unbalanced, then good again.  I have had bad sounding out of the box, then they got progressively better. 

Another technique that can accelerate break-in is using a Purist Audio Design Ultimate System Enhancer disc.  They claim that for every hour played you achieve 5 hours of music play break-in.  I use that disc to help with burn-in  anything new in my system, including tubes.

Right-O! Not only that but these burn-in CDs like XLO and Purist demonstrate that cables never actually burn in completely without using the burn-in discs, you know, since using the burn-in discs on what are assumed to be very well burned in cables, even ones in everyday use for years, improves them significantly. Sha-zam!! So, how much do cables burn in listening to music? Well, you tell me. My guess is 75% max.

I will limit my comments to quality build cables, because cheap budget cables that I personally experienced max out very early in the process and don’t follow the same observations following

I disagree that any proper or definitive audio performance evaluation can be gleaned from any fast first plug -in /swap-in bake off . It won’t give you any proper gauge of ultimate performance.

It took 350+ hours for my high-end model NORDOST cables loom to break in substantially (90-odd %) of peak performance , and it was not any linear pathway to OZ.

Rather it was an ad-hoc series of incremental steps . There were numerous flat plateau periods, and then I would be pleasantly surprised with another "new" improvement that made it all sound better.