Onkyo 875/PS3 Blu-ray decoding

[axe79]

Help!
I have this along with a Monitor Audio RS8 5:1 speaker package. Fed by a dedicated Mains Spur with Mains Transformer Conditioning and cables. The sound quality is foot tapping superb, properly set up in a well furnished room.

I play Blue Ray films, but they all sound much better sent Bitstream to the 875 and processed by it (timing, cohesive sound stage, presence!)

Now I am not getting the benefit of MA/HR as the PS3 will send it only on LPCM am I? Though I can't hear any loss of detail between the two.
So my Amp is not getting the full package of data is it?
I do understand the importance of the Burr Brown DAC's in the Onkyo getting a pure feed, is there some signaling issues at play here?

From what I know the PS3 doesn't have a chip set inside it to package on bitstream all the info on BR whilst other newer players have.

What am I actually getting and why does it sound so good, surely DD is not a patch on Blue Ray HD-MA or HR?