So, I just received mine, and I must tell I'm really mind-blowed by this little thing
Compared to my smartphone (an Honor 5C, which has the reputation of having a good Jack audio quality for a sub-200$ smartphone), the M0 is of course like day and night. But I think it's also a step above my Asus GL503VD, a gaming laptop which has a really great Jack output.
And this audio comparison stands for Bluetooth mode, with SBC codec (my current phone is running Android 7, so I have no other choice), so I can easily guess how the M0 would perform with FLAC files.
The only downside when I used it was the Jack of my Sennheiser Momentum were unplugging very easily ; a very simple pression on them would slightly unplug it and so I would have music in only the left ear. That pretty disappointed me, until I figured out I could push the Jack further in the M0's port ^^ I was a bit afraid of pushing it too much, but in fact it's required in order to correctly plug the headphones in.
So, after testing a bit of Epic, Rock, Metal, and Classical (basically Introduction and Rondo Cappricioso from Saint-Saëns, the Ballade n°1 from Chopin, and a few others) I find it rather musical than analytic: I can easily separate the instruments in my head, but that's not a precision DAP. Rather, its musical side is really enjoyable, as you just have to listen & enjoy.
That's my very first DAP, I was a bit afraid of the audio quality since this is only a 99$ product, but it's really worth the price. Thanks again to Shanling for this great product