All I know is that it needs to be on bitstream is you wish your amp to output a digital signal,be it DD or DTS.
I thought PCM (Pulse Code Modulation I think) is what you standard CD works on.
Someone with alot more up top will no doubt correct me
And could that someone also give an answer to the question: what the difference is between transfering a PCM-signal by selecting PCM also as transport-code versus selecting 2-channel analogue transport-code?