As as far as I know HDMI 1.3a is suited perfectly for DD+. 1.4 is needed for 3D TV.
From my experiments I can see that when duo2 is connected with optical, sound is downmixed to DD. When it is connected with HDMI (1.3a amplifier) sound is DD+ but it might be not a raw bitstream from satellite/terrestrial (AUDIO_CONTI[AUD]: DDP downmix 1 state : 1 log line).
From my experiments I can see that when duo2 is connected with optical, sound is downmixed to DD. When it is connected with HDMI (1.3a amplifier) sound is DD+ but it might be not a raw bitstream from satellite/terrestrial (AUDIO_CONTI[AUD]: DDP downmix 1 state : 1 log line).