Hi
As far as I'm aware ARC over HDMI or using optical only, supports standard Dolby Digital or at best 2 chanel PCM stereo (CD quality).
I know on our Humax PVR that Dolby Digital+ is converted by the Humax to standard Dolby Digital. The Samsung TV may do the same and it may show up as normal Dolby Digital which is as good as the same thing. Check the audio settings of the TV and see what it allows.
It may just provide standard stereo however, in which case I don't think you will ever get Dolby Digital+ out of the TV.
Regards
Phil
