I had to hunt around a bit for this one.

Fellowship of the Ring EE was easy enough to test. Internal decoding treated it as a DTS 5.1 track and bitstream output provided the processor with a DTS-ES stream. It worked fine.

I had a harder time finding a true DTS-HD 6.1 track. I have several DTS-HD MA tracks that are listed in Blu-ray.com as being 6.1, but based on the disc cases they are actually 5.1 tracks with a DTS-ES core track. (Wall-E is this way - it's a curious discovery that we made during beta testing.) I did find one DTS-HD HR 6.1 disc. The BDP-83 identified the track as DTS-HD HR 6.1 and decoded the track to LPCM 7.1. I had to hunt to find a scene that had any surround activity, but I was able to verify that the channels were all working.

I will have to look around for a DTS-HD MA 6.1 disc to see if there's something different happening with Master Audio tracks.