Originally Posted by dndphishin
My cable box's 5.1 DD optical audio is better than anything I can get from BR downconverted from the Oppo optical out so far. And it's a bit odd, as everything else out that optical pipe sounds quite good. I figure it's either the downconversion process - or a setting I need to play with.......
That's strange, because the Oppo should be using the DTS core from DTS-HD MA or the supplementary AC3 track from TrueHD soundtracks, when sent via SPDIF output: there is no "downconversion" occurring, simply sending out the digital "cores" unmolested.
However, if you set the SPDIF output to LPCM, then you will only get a stereo downconversion of the original tracks.
There is a setting for activating secondary audio: when this is active, the primary soundtrack is decoded and mixed with the secondary audio, then either downconverted to stereo (if LPCM is selected for SPDIF) or encoded to DTS (if bitstream is selected for SPDIF).
It is possible that you are losing some audio quality in the DTS re-encoding process if SPDIF is set to bitstream and secondary audio is activated.
You surely would be losing audio quality if downconverting audio to stereo LPCM when LPCM is selected for SPDIF.
I would suggest ensuring Secondary Audio is set to OFF and SPDIF set to bitstream and see if that makes a difference.