With blu-ray disc players and uncompressed HD audio you’re going to find that the “digital coax” and “fiber optic” will only transmit standard “Dolby Digital” and “DTS”. You will NOT hear uncompressed when using these connections.
HDMI connection or 7.1ch AUDIO OUT supports UNCOMPRESSED Digital Audio transfer.
(When using an HDMI cable, make sure your “HDMI Digital Audio Out” in your Blu-ray Disc player’s setup menu is set to “Bitstream” and not “PCM”.)
The “dts-HD Master Audio” is the best, followed closely by the “Dolby TrueHD”. The “Uncompressed PCM” is leaps and bound better than standard “Dolby Digital” and “DTS” but not quite as good as the other two HD Audio formats.
Be sure to pick up the newer (and less expensive) PS3 “Slim” to get the best audio quality from your Blu-ray Discs.
The original PS3 would decode “TrueHD” and “Master Audio”, but down-converted both signals into “LPCM” before outputting them over HDMI.
The new PS3 “Slim” sends both “TrueHD” and “Master Audio” signals completely unchanged over and HDMI cable to your capable receiver.