Dolby 5.1

[adm]

Miracle Premium Twin HD - various VIX Apollo builds 030 to 39

When viewing a Freeview (UK Terrestrial) HD program with Dolby 5.1 audio what audio standard is output from the Micraclebox Premium Twin HD on the HDMI and on the S/PDIF (TOSlink) optical sockets.

I have an old (pre HDMI) Onkyo AV amplifier with only S/PDIF optical/coax digital inputs and can only get the Miraclebox to output audio if I set the AAC downmix to 'yes'. This doesn't give 5.1 over the S/PDIF (TOSlink) link which suggests that what is coming down the link is in a 2 channel PCM format.

If I could connect an AV amplifier via HDMI I would I get 5.1. via 5 channel PCM?

Or is the output format something else?

Some background for my conclusion (which may be incorrect) can be found in posts #5 and #16 from:

http://forums.digitalspy.co.uk/showthread.php?t=1761159

I also base my conclusions on the same AV amp being connected to 3 other sources of Dolby 5.1 which the AV amplifier correctly identifies as 5.1 because it is coming down the S/PDIF (TOSlink) links in a different format.