Re: DTS MA DD TruHD and BDP-S550
The table on page 66 shows what the player outputs for each format, for each output method. If you look at the HDMI column, it states "LPCM 7.1" for almost every format. That means it is output in LPCM through the HDMI interface.
Look, however, at the "Multi Channel Output" column. It simply states 7.1. Assuming the graph is accurate, it seems that the only way to truely get a lossless decoding from the player, for instance DTS Master HD, is through it's analog outputs. You would assume that DTS Master HD decoded signal would still be better than regular DTS, but I can't really speak to it as I have always had a receiver that did the decoding.
Most of the player's manuals have a similar graph. I always go online and look at the manual for the player that I'm wanting to get, and look at this graph to see if there is any insight into how the players decodes the audio.
It's not really straightforward, but if you get a receiver/preamp that does the decoding and handle it through the bitstream method, it seems to work every time.