On speaker break-in:
I didn’t think much of it as I’ve never really heard my new speakers change much at all. My Salk Songtowers sounded pretty much the same. I thought the sound may have changed (eased/opened up) but it did not really take up too much of my time thinking about it.
Recently, I bought Tannoy Turnberrys. I set them up but noticed I had not received the grills. Maybe there was 3rd box I didn’t receive? Anyway Upscale Audio offered to replace them. I listened to them and they sounded a little shouty but pretty damn good. Over the 50 hours, they seemed to sound more open and less congested. Maybe these speakers actually need break-in?
The old speakers were replaced and it turned out I had received an open box set as the new speakers came with grills and the accessories were in sealed plastic bags.
Well the new Tannoys sounded like crap. Really congested. Not even shouty. Just terrible. It was not anything subtle. 10 hours later, I got shoutiness too. Got that for another 15 hours. 30 hour mark and things started to sound exactly like the open box speakers. 12 more hours and things had smoothes out and bass was effortless.
Now I think speakers with butyl rubber surrounds will probably sound pretty close to the way they started but anything with hard surrounds or the double-rolled and doped cloth surrounds like these Tannoys will need some mechanical break-in.
I do believe people who need to ’measure’ everything in life before they believe anything should measure a hard surround speaker before they they seem so sure it is a myth.