I was struggling with sound passthrough until I found advice on the forum here to install firmware with reset. I had installed 1.09 but I updated Kodi from Google Play to 16.1 which caused my problem with passthrough. So to go back to Kodi which allow passthrough I did not reinstall firmware but from Android setting I wiped out all data so reset. It gave me back a plain Android and Kodi 15RC which is modified by Himedia and has some exclusive codecs. Before reset I had passthrough with some strange noises or pausing sounds in Kodi and now finally I have all wanted HD 7.1 sounds (even Atmos) with HDMI audio output in Android but not with s/pdif out. In native Android's player is opposite- s/pdif output has passthrough HD audio on the receiver (Onkyo nr747) but not from HDMI and no Atmos at all .
I have computer with Windows 10 64bit on the network and it has all drives protected with user rights, passwords and shared folders and H8 had some dependency between Android and Kodi; if I will try access my videos with SMB from W10 on the android it will ask for the password but won't let me access the files, if I will do the same in Kodi it let me establish folders and access them but only if I earlier put user and password in Android, otherwise no access. So now I'm happy with the box. Other thoughs: I liked better colors and brightness in Kodi 16.1 and 15RC has smaller video frame than frame of my 65" 4K TV (I do not know if is adjustment for it), but passthrough is for me more important, and probably will be soon Himedia firmware with Kodi 16