IMO if something needs "breaking" or "burning" it should be stated in device manual. I can hardly imagine such necessity, however. Personally I put it to the drawer "MYTHS". If some devices really would need any "braking" or "burning", whatever, it would mean that it was poorly designed, or was intentionally designed with the use of materials which are unstable, resonant or prone to aging. Just think: if driver suspension needs to be "settled" - doesn't it suggest that the material is improperly chosen? Or it was build intentionally like that to achieve some specific goals, but that should be plainly put in the manual.
If the sound of any audio device - hypothetically - is to change in first 24 hours, what with the rest of its lifespan? What is logical explanation of this phenomenon? LOGICAL - it means with the use of science tools.
However, I see some cases when "braking" can be observed, like TUBES. But, again, the user should be warned that the sound perception can change in time because of the device electrical nature.
The sound perception is a very misleading human sense, what everyone here probably know. We all are prone to suggestions and marketing bullshit. And there is an internet... with incredible amount of INFORMATION, information and "information". Choose what you like.