Meizu non pro owner here to report my findings:
-the millisecond cutouts can only be heard on Android and with UAPP. YouTube, Spotify, SoundCloud, Neutron, all are fine on Android. On Windows as well, I couldn't hear any pops even with foobar Wasapi output.
-HW volume steps: I recorded a 1000hz sine wave and did a volume sweep in UAPP. Then I opened it in Audacity and counted the now visible steps. Halfway through the recording, at 52 steps, the Dynamic range of my recorder can no longer see any steps, but it should be 100. Windows will actually recognize the HW volume function and the normal SW volume bar in the bottom right corner will automatically switch to changing the Meizu's HW volume. Here as well, every numerical step (e.g. 14-->15) represents an actual volume step reaffirming 100 total.
-strangely, Windows will not recognize the Meizu dongle as an Audio output device unless a headphone is plugged in. If it's not, Windows will list it in "Other Devices"
-Output Power: with foobar playback, 1-2%, maybe 3% is all that you get with 102dB/mW Blon BL-03 IEMs. Everything above that is too loud.
With 105 dB SPL/V AKG K712 Pro headphones, you'll be listening at between 4% and 8% so im really clueless as to why Josh Valour thinks theses are power hungry.
-UAPP fix: I wrote the UAPP devs about the problem and they are aware of it but sadly don't see a fix possible in the near future. The problem is that the Meizu DAC only handles multiples of 48kHz correctly. Everything else causes stuttering. HOWEVER, by enabling upsampling in the USB audio settings and disabling bit perfect output, the issue is gone. No more cutouts.
If you want a recording of the cutouts or the volume sweep, just tell me and I'll give you the link.