Originally Posted by abuttino
I am unsure of the difference between LPCM and PCM, but I believe it is the same thing in principal. The few disney movies I have with LPCM (Cars, Pirates of the Caribbean 1, 2 and 3) have a better soundtrack than what I hear when downmixed DD+ to PCM.
Pretty sure too PCM and LPCM are the same thing i.e. totally uncompressed lossless audio. My amp seems to use PCM to indicate stereo and LPCM for multi-channel though I am not sure if this is a universal convention.
The way I understand it is everything is output from the CC as (L)PCM, having been delivered by Plex as AAC. So if you are saying your DD+ is getting down-mixed to emerge as (PCM) stereo then that should not be happening and will certainly sound way inferior to the original multichannel track. It should be getting output as 5.1 (L)PCM.
But even this is not going to sound as good as the soundtracks on the titles you mention since LPCM from the original source will be as good as it gets - delivered to your amp completely untouched, blank space and all. The (L)PCM delivered by CC to your amp is different to this though. This audio has already been compressed to DD+ and then converted by Plex to AAC. But, as Asphyx has indicated the resulting stream from the CC should sound, as near as makes no difference, just as good as the Dolby if it is getting properly transcoded.
It would probably be worth investigating further if your DD+ is actually getting down-mixed to stereo and if so why. Also, most of us using Windows did have a problem of missing rear channels when CC support by Plex was still in beta. That was soon sorted though, who knows, maybe not for some DD+ users?