Merely opening a port will change the sound of any speaker: the enclosure, the material. I wouldn't be that surprised if many of the popular IEMs sold shares the same driver, also I really doubt the Chinese companies are making new drivers every time to put into the "diy" versions. About the balanced armature used (with the exception of xiaomi maybe) they are probably copying some of the Knowles designs already tested. Who are we trying to convince? Don't fool yourselves.