With the iOS latest update, the iPhone/iPad can now play high res files natively! I’m able to copy over a high-res 192 AIFF track using iTunes and play it natively on my iPhone using the Music app!
Previously, you could only play up to 48Khz files natively. (There were third-party apps that could do it).
If you’ve got an Android phone, the free Onkyo HF player app will also do this.
That’s the app I was using on iOS previously. I like the Music app user interface much better though it does not have EQ function (which I use on a rare occasion).
The Onkyo HF player still has the advantage of DSD playback and upsampling too.
What file formats will IOS play? It used to be limited to Apple formats plus MP3.
I know it can play wav, aiff, ALAC and mp3. Not sure about FLAC (maybe not).