I’m thinking of leaving a FB group called Chifi audio reviews because daily there’s people asking the same unfounded questions about what cables sound the most transparent, or tame treble, or increase detail etc. Sometimes it’s the same thing but about DACs which I almost understand (shitty outputs can make headphones and IEMs sound thin and lean but I think that’s just a matter of bad designs). Burn in is another such culprit. Do just a couple of minutes of searching online and you’ll be presented with facts and reasoning telling you it’s bunk.
It drives me nuts, it’s like having flat earthers and scientologists everywhere in the hobby everywhere I turn. It’s slowly driving me nuts, lol.
As far as burning in headphones go, I don’t think it’s bunk at all. The data signal through a wire being better or worse can be bunk, but it depends on how much resistance is occurring in the cable…not likely enough to affect sound quality.
But with actual animated components like speakers, there could be benefits to wearing them in (burn in). Anything that moves will eventually wear out. A car engine requires a break in period because components are new and can loosen over time. Same goes for the diaphragms of speakers and the voice coil that moves back and forth on a magnet. Over time the material that makes up the diaphragm can loosen up and alter the sound produced.
When the voice coil moves back and forth on the magnet, it can smooth out microscopic pits and grooves making the voice coil freer to push air more efficiently.