Yet another post proving you know shit all about anything headphone related. There's a reason Etymotic has had the ER4P/S/B the same the past 20 years, they haven't found the need for unnecessary complications like multiple drivers with crossovers. Shut up and do some reading before you further make a fool of yourself.
Etymotic Research, Inc. - Technology - How We Measure Response Accuracy
Etymotic Research, Inc. - ER-4? MicroPro Series