[terminal pharmacy]

this says it all -

 

the graph shows the frequency response to be woolly. the whole burn in thing is a falacy. i have never had to "burn in" iem's or any speaker i have ever worked with. do not play a sawtooth wave through the speakers for an hour a day this is bad information. it does not get all the frequencies "going" as a saw tooth does not cover the frequency spectrum like that. if you really want to continue to "burn in" you iem's and cover all the frequency range of the iem's then use pink or white noise. personally if the don't sound good out of the box and you need to "burn in" the voice coils then there is something wrong with them or the design.