1. OnePlus 5T
2. Oxygen OS 5.1.4 (Android 8.1) - this is the current release of stock ROM
3. Hi-Res 24/192 output works after phone reboots. However sometimes if playback is stopped and resumed, or headphone is unplugged and plugged back in, sometimes sound plays through phone speaker instead of headphones. Poweramp detected headphone is plugged in, and in settings says it is playing through headphone using 24/192 direct HD, but sound is coming out of speaker. Rebooting phone solves the issue. Problem is random and doesn't happen every time playback is stopped/resumed or headphone is unplugged/plugged but when it does happen, playback through headphone cannot happen again unless phone is rebooted.