Two issues with H6 HDMI audio were fixed - right channel not working and audio rate was not exact so audio was probably slightly distorted.
Please test following update and report if it works (valid for all H6 devices): libreelec-h6.arm-9.80-devel-20190914184226-e4aa9d6.tar
If it works, I'll PR changes to main LE repository.
Tanix TX6 mini
Audio now is louder and better, same as on OPI-PC.