dharmasteve
Headphoneus Supremus
to be honest I don't know enough about audio engineering to understand why it happens, but @Sven2015 explained that it has something to do with the preamp not being set to -6dB. It seems like something that should be fixable via firmware and I've alerted FiiO but again I'm surprised that the device made it live like this.
If you have an M9 you can try this track to see if it clips: https://www.dropbox.com/s/512kto98uozyj6t/02 Long Road No Turns.flac?dl=1
I've also noticed it to a lesser degree on music of varying different genres, e.g. the new Earl Sweatshirt release. but on this song it's particularly jarring.
Interesting. I played your high quality flac file, but then I tried the track streaming through Spotify which is a lower quality OGG, yet the OGG sounded clearer and with more separation than your flac version. Possibly it's the track rather than the M9? Check it on another DAP maybe. I'm sure it did not clip on mine though.