The FIIO FA19 is designed based on both science and actual listening tests. For the FA19 we settled on using these drivers per ear: 4 custom Knowles bass BA drivers, 2 Knowles ED mid BA drivers, and 4 Knowles SWFK treble BA drivers. Having more drivers in an IEM does provide certain advantages. It significantly increases the energy density within a given frequency range, resulting in more detail reproduced. This is especially apparent during dynamic audio passages, where more drivers are better able to handle the nuances present, ensuring that the resulting sound is not compressed. And thus, the IEM is better able to faithfully reproduce the original sound.