I have a BV7-55 without the built in BluRay and use an Oppo, but don't the specifications from the B and O web page specifically list True HD7.1 under Supported Audio Decoding Formats? This would match what Beolion posted "I think that the blueray player in MK1 (which I have) can decode Dolby TrueHD, but not DTS-MA. The player in MK2 can also decode DTS-MA."
Yes, that would seem to be the case. Perhaps they changed the mechanism when they upgraded the TV with a 3D panel and, as a result, the upgrade also supported both True HD and DTS-MA? Still annoyed I parted with an extra £1000 with my BV7-40 purchase, to get internal Blu-ray and it wasn't supported but, in hindsight, an external Blu-ray player was likely to be a wiser idea (so perhaps I'm more angry with myself than B&O!).
One thing I need to do is rip some of my Blu-rays to my NAS drive.