9.Is it necessary to burn in the FH3? What are the skills and requirements during the burn-in process?

Because of the working principles and characteristics of the ear unit's speakers, new earphones usually need to be burned in for about 200 hours which can keep the speaker diaphragm working at the best state.
In general, users can choose songs of soft style they often listen to and keep the volume at a middle level until they are satisfied with the sound of the earphones.