> If it "miss" you will ear it. So there is no invisible danger, it cannot be not perceptible

not always true. Minor phase mismatch will create higher frequency sound. You wouldn't hear ultrasound, though how bad it is to have an ultrasound source in you ears i don't know.

The phase mismatch can be temporal - circuitry reacting either a bit too fast or too slow - as well as spatial - the sound wave front most probably aren't parallel to the speakers frontal plane.