1. Sony Xperia XZs (G8232)
And also: XZ, XZ Premium - all this phones are the same.
2. Android 7.1.1 (Xperia Stock Room 41.2.A.7.53) (but Oreo will come soon)
3.This information is wroted at Sony's official site. Also there is a "DSEE HX™" (I don't know what is it).
https://www.sonymobile.com/us/products/phones/xperia-xzs/
4. My audio_policy.conf: audio_policy_configuration.xml
and Build.prop: build.prop
I like Poweramp - it's the best player ever for Android. Thank you for you work. I don't regret, that bought it a few years ago.