That’s a new one on me. My brother has always been majorly into electronics, and if he knew anything like that, I’m sure I would have heard it, too. And I have two sets of headphones, and they didn’t need “breaking in.”

I have never heard of that. If it were true, manufacturers like BOSE would tell you “how” to break them in.

And if it were true, the same theory would apply to regular stereo speakers.

There is a group of audiophiles that believe “breaking in” is required of new speakers and headphones.

I’m not one of them.

Audiophiles will say yes. They act like everything needs “breaking in”, even a digital cable.

I haven’t found it’s made any difference, even with high-end headphones. Breaking in-time does make a difference with turntable cartridges, but that’s about it.