Asit u are not wrong in what u do. Playing music normally even in the initial hours of acquiring HIFI(amp,cdp and speakers) is not wrong and break in occurs gradually. The other methods suggested (wiring speaker out of phase) etc are more followed by dealers as they want to speed up the process as they need to demo them at the earliest.
Regarding a new car it is advised to not go above 3000 RPM till u cross the first 1000KM and avoid sudden acceleration and hard braking. Its more about engine RPM than speed. Taking a new car to the red line is disaster as there will be a lot of friction. When we were in the Fiat/Maruti 800 era one could sometimes see metal fragments in the first oil change but modern engines are built better.
I follow a set pattern in all vehicles. Obviously i drive it carefully and dont strain the new engine, i also change the oil every service (1st, 2nd and 3 rd free service) even if its not neccesary and swap to a synthetic oil (Mobil 1 0W 40) after about 5000 Kms. Have had very good service from all cars there after. The more u are careful in the first 1000 KMS the better the car will perform in the years ahead. Sorry moderator for the car talk but cars/bikes are a greater passion than HIFI for me!