I wonder if anyone has performed a proper controlled study of ‘running in’ hifi equipment whether it be speakers, electronic equipment or analogue sources? While it seems more plausible that components which move, such as speaker cones, could benefit from doing this than, say, electronic ones (ever ran in a laptop?) I have yet to be fully convinced of its benefit in any situation.
I say this because I wonder if it is actually our ears/brains which are being ‘run in’ rather than the equipment, by which I mean we simply become more accustomed to the characteristics of the component over time and wrongly ascribe this ‘improvement’ to the equipment bedding in.
I have observed this most often when changing back to headphones I have previously used. Suddenly the original raw edges are there again until I get used to them once more.
It would be fascinating to conduct a study which objectively tests this
It is both interesting and almost undoable because one needs to go thoroughly through a double blind research that in reality no one will conduct scientifically asides from some heavily biased audio geeks who want to proof what they think and favor measures that support their claim above others.
To throw in some science one can do without testing I would advise to explore the way back in time with a rough question like "till what period or for what equipment did technicians describe burn in time?"
That answer is easy to explore. Tubes need time to warm up every time, so they need to burn in to sound at best. And what were the most common, if not the only amps till a point? Tubes. And not only in audio, The first CRT TV's were quirky and often needed a little time to stabilize too. Luckily we are past that age.
In this context " let it burn in" really applied to a set of speakers for a 100% related to to the tubes they were connected to for a minute or 10(?).
There might be more systems that need a little warm up time. Perhaps systems like electrostatic speakers (?) , though I have no practical experience with them so I will leave that to the experts.
Flexing rubber of a speaker is not really burning in. When I use my speakers at reasonable living room levels I barely see them flex. Maybe in that context of modern speakers "burn in" became more of a sales advice in order to give a customer the message "your brain will get used to the sound signature" as little changes might be there and getting used to a midrange focused speaker is a thing when your previous one was boomy or bright. Then you might need to re-explore your library to hear new nuances.
In the end, commercially spoken and in a modern sense "burn in time" is the idea that a customer doesn't return the product the next day, just because he or she experiences a signature difference.
p. s. I would like to point out that audiophiles often buy second hand speakers and state "I don't know if these were burned in or not, but I assume they were". Which on its own kind of destroys the whole point at its core.