I have some MKVs with DTS HD MA audio tracks. For these movies, the center channel is playing on the right front channel. In the PS3 app, I have 'Dolby Digital (AC3)' checked. I have tried it both checked and unchecked.
I understand that with MKVs and DTS, the plex media server is doing the transcoding, and I see on the receiver that its coming from the PS3 as PCM.
This only seems to be a problem with my MKVs that are DTS HD MA, those with dolby digital tracks are ok.