mi6 uses wcd9335, an old scheme of Qualcomm, which is relatively backward, and the sound quality is average, which is equivalent to the castrated version of audio decoding 835. WCD9341 is much better, Samsung S8, S8+ and HTC U11 are in use. Neither of them is a professional HiFi chip.

In fact, mobile phone audio is not related to HiFi. Even vivo, Meizu, hammer, etc. using professional HiFi chips are far from HIFI, which can only be said to be slightly better.