I have made some very good buys on things 2 weeks old that the owner
gave up on. My Pass Labs INT 25 was a good example.
Shunyata developed their own system for burning in cables
because people are impatient and give up too soon.
It varies from equipment to equipment, ime. Some DACs, i could never notice a sonic change. The manufacturer could have burnt it in before they shipped some models.
Yamaha amps, for example, go through a distinct change in sound after around a 100+ hours of use. It was clearly noticeable on my former A-S2100 (which i didn’t record). I made it a point to record it on future Yamaha amps, i.e., 0hr playback and 100+ hours of playback on my former A-S3000 and current M5000 to prove that i wasn’t losing my mind. Pass amps, the break-in is a bit more subtle, not as blatantly obvious as Yamaha.
Speakers can be fairly quick to break-in depending on how you do it...
The whole "it takes months and months to burn crap is the dealer pulling a fast one for closing the return window. If he made his 10k+ cut on something, he certainly doesn’t wanna take a return.
On a different note,
@mijostyn , Here’s a video on how to measure driver break-in for your viewing pleasure. Try it/experiment with it/measure it yourself at home with a couple of new drivers.