18.Has it been improved when Q5s is matched with FiiO android player, such as M6, M7, X7, M11, etc.?

The sound quality and direction depend on the type of DAC and amp, so the final sound quality output after the player will have a difference in hearing, but it has great improvement on using with M6 / 7. After all, the sound quality is subjective, it is recommended to try listening at the local physical store if you can.