I have an Loewe Compose 52" as well... I'm planning on connecting my BeoLab 8000's to the TV (and more BeoLabs too in the future).
Been doing some research and came across this cable: http://www.av-connection.dk/?PGr=1760&ML=328
It has an Powerlink DIN in one end, and phono + trigger in the other... so by connecting with this means that the speaker's on/off-function will act just like it was connected to a B&O system.
The ony thing is that you will have to change the little white "box" on the Loewe Audio Link adapter to a 3,5mm female mini-jack.
Check out this gallery for some pictures from a guy that has done this: http://www.minhembio.com/beomac/164461
And as for sound from Blu-Rays, DTS-HD etc... I don't think the surround module in the Loewe supports that, but it does however support PCM... so just set your Blu-Ray player to output as Linear PCM and it shouldn't be a problem :)