Frankly, is it the speaker that requires break in or is it your ears and brain that are the things that are actually "breaking in"?.
Probably, a bit of both ... depending ...
In the next post I'll share thoughts about the ear-brain evaluation question
I have never bought into the idea of hundreds of hours of break-in time required for anything especially amplifiers that the so-called 'audiophiles" claim is necessary before things start to sound better.
I’m for the most part with you …
Most solid state devices are not going to change much with break-in (Note: you can wear out some solid state parts like SSDs but for the most part I’d need some convincing on it changing a transistor's transfer function). I can understand needing some time to warm up as temperature changes effect components. I can also understand that in a poorly design circuit having components change because they are being stressed. Most solid state designs I've worked on were run for a few hours to reduce infant mortality, as most components have a higher fail rate early-on. By "burning-in" for a time you can bring that down to a reasonable rate. Maybe someone more in the know on this can come up with something here. I've just not seen it.
Mechanical systems wear, sometimes for the better and sometimes not. I can definitely see how a stiff speaker could loosen up or a material become more playable by wear. How much depends on the system and the materials.
On Tube stuff, I’ll take a pass, just don’t know enough in this area.
