5. Why not use the MMCX connector?
It is widely used for most of the third-party earphones with an MMCX connector. Needed an expanding connector to assure the reliability, the MMCX connector cost more than the 2-pin. In addition, customized earphones normally use 2-pin connectors due to the specificity of resinous material. Therefore, in order to control the cost, we have to give up the MMCX connector.