2. What is the sound tuning style of the FH7S? What type of music is it suitable for? What are the differences between FH9, FH7 and FH7S?

The bass of the FH7S inherits the tuning style of the FH9. The low frequency dives deeply, and the transient response is fast, which makes the interpretation of low frequency more surging, and makes the sound performance natural and solid;
Mid frequencies are handled by the custom Knowles BA, which adjusts the air permeability of the midrange drivers, thus leading to clearer vocals and a more engaging tonality.
The high frequencies are produced by the Knowles SWFK-31736 BA driver with its high resonant frequency. The driver contains richer highs details and airiness while also helping to further enhance the size of the soundstage, which is relaxed and comfortable to listen to.
In terms of the acoustic structure, the development team created a unique notch filter for the FH7S by using finite element analysis and after numerous experiments. The notch filter precisely guides sound waves to eliminate unwanted resonances between the shell, sound tube, and ear canal to suppress undesirable sibilance - resulting in a detailed, transparent yet unfatiguing sound.
Included with the FH7S are 3 tuning filters, each of which has its own damping characteristics and filter density for 3 distinct sounds, so that you can choose the one you like.
To sum up, the FH7S is an omnipotent candidate. Whether for pop music, rock music or instruments, especially classical music, it allows for an amazing experience with large dynamics, just like you are listening to live music.