9.Is it necessary to burn in the FH5s? What are the skills and requirements during the burn-in process?

Because of the working principles and characteristics of the unit speakers, new earphones usually need to be burned in for about 200 hours so to make the diaphragm work in the best state.

In general, you can choose some softer songs and keep the volume at a medium level until you are satisfied with the sound performance of the earphones.