The new FH19 from FIIO is a significant upgrade, incorporating much user feedback. It retains the signature sound and flagship-grade craftsmanship of the FH9, and is also co-developed with Tokyo Onkyo Ltd. in Japan and Knowles in the USA. It features a truly high-end acoustic design, with richer and fuller midrange and more robust yet flexible bass. Additionally, the fit has been redesigned and optimized based on the characteristics of the human ear, allowing you to experience truly flagship-level comfort. FIIO, in collaboration with Tokyo Onkyo Co. Ltd., has developed a push-pull dual dynamic driver unit for the FH19, based on push-pull technology used in high-end audio. This technology employs two 13.7 mm high-magnetic dynamic drivers with PU+DLC composite diaphragms, arranged in an opposing configuration. Compared to typical dynamic drivers, push-pull dual dynamic drivers require only half the amplitude to achieve the target sound pressure level. The FIIO FH19 uses six Knowles balanced armature drivers as its mid and high-frequency sound units. In order to achieve even higher levels of vocal sound quality, FIIO collaborated with Knowles to create a custom mid-frequency-enhanced balanced armature driver.