Now, the latest version 790 seems to work properly with Open ES HD Output.
However, when I use Hi-Res Output, the volume is very low. Besides, although I choose to open Hi-Res Output, it seems that Open ES Output is active rather than Hi-Res Output. Just as follows, Open ES Output shows active, but I set Wired Headset/AUX active in Hi-Res.
By the way, I want to know whether Open ES Output is only for Android 8.0+. It seems to work properly in my device which system is just based on Android 7.1.1.