I think, it doesnt matter even a bit, if the device is capable of 24/96 flacs, or "only" 16 bit flacs...
Even the difference between a good 320 kbit/s mp3 file and a flac file should be so small, that its mostly not hearable (yes, even with 400-500€~ in-ears/headphones !) depending on the sound file itself.
The DAC/Amp might be very good for a smartphone, but this is STILL "just" a Smartphone.
This is not comparable to a true hifi DAC/amp, like lets say Yulong u100, Audio-gd, Fiio (even if those are cheaper), matrix, and models like that. Even on those the difference shouldn't really be heared. And if, then only just slightly.
Which means.. i dont care if my device can play 16 or 24 bit flacs. It can play flacs, end of story. such details wont change anything on "just" a Smartphone.