Being a bit more critical in what I'm seeing/hearing
There seems to be a lip-sync problem between vision and ACC downmix audio over HDMI and SPDIF that appears uncorrectable on the Miraclebox Twin Premium. There is a PCM delay option in the AV menu with a range -1000 to +1000 but this doesn't appear to make any difference to the mismatch (audio ahead of vision).
What I'm observing is with a TV connected via HDMI and using the TV (non-surround) audio/speakers, and as a second test with SPDIF audio into an AV amplifier.