It's not as smooth as my iPhone. It's way more smooth than other DAPs I've seen / had in the past. Stutter in the Mango player (the default music app) isn't there, some lag is (mostly in the interface). TIDAL has no problems and runs fluent (so far). TIDAL also does the MASTER / MQA thing fine (v2.11.2.885.3).
Oreo in general has some hiccups from time to time, but they are very small.
I quickly tried the FiiO Music app and the Hiby Music app two days ago, but didn't like them. However: I can't remember those apps having stutters or lag, if they did behave
very poorly I would remember that
The only thing I have to get used to, is the touchscreen, I have to press a bit more conciously / harder than I'm used to on my smartphone. Is it a dealbreaker? No. Not for me.
Also something to keep in mind, the current iBasso-Oreo release is about 1 month old, so it only seems fair (to me) to give iBasso some time to come up with new firmware releases and updates to further enhance the experience.
Besides everything above, and this may sound a bit stupid: but it is
just a music player (a good one, mind you). It does that well.
If you want good / better audio without worrying about performance, maybe look into a Dragonfly Red from audioquest, Chord Mojo which you can hook up to an existing device or one of those LG phones with build-in DAC/Amplifiers that are better than average. Every DAP that runs Android and comes out of China will "have some problems", you just have to accept that or look for another solution. You could also look into players without streaming functionality, and basically buy an "iPod on steroids". I believe Sony makes good players that are not running Android, so maybe something to look into?
Hope this helps!