Hello,
First, thx a lot for your work.
I try to use HD audio on my mx3plus. I used it from android with vidon xbmc player.
I tried last v7 and v8 from clean install but i can't see the HD audio passthrough checkbox in audio settings. I notice that HDMI is not listed in the output choices. There is only Analog and Spdif choices. However DD and DTS work fine through HDMI.
Ask if you need some logs.