I have checked a few things.
I have the Edge with Captain board. Using GPIO pins 13(SPDIF Sig) and 14(SPDIF GND), to my Onkyo HT-R391 I get 5.1 Dolby Digital. Works well.
I assume this will also be true on the Edge-V. Android Settings/Device Preferences/Sound/Bitstream/Audio device, set to Spdif Passthrough…
My Edge is running a Custom ATV ROM built by @mo123…
The ROM is available here.