In theory, the Blu-ray spec has room for a special "Profile" that would be audio-only, similar to the Profile 1.0, Profile 1.1, and Profile 2.0 players that we've already had. In reality, nobody seems to want to develop the standard enough to define this profile, so it's doubtful we'll ever see a "Profile 3.0" Blu-ray audio player - which makes sense, since Profile 2.0 players should be sufficient for any audio-only disc releases that get created.

Studio recordings have generally been released with video that includes a static slide for each track. As for the audio track, Blu-ray supports so many lossless options that there's no need for anything special. TrueHD and DTS-HD Master Audio can be stereo or multichannel, as can uncompressed LPCM. Any of these will work. In some cases, discs include both a multichannel track (TrueHD or DTS-HD MA) and a PCM stereo track.


HDMI requires HDCP, so once you have HDMI you have copy protection. That was enough to convince Sony (the primary force behind SACD) to allow digital output of SACD over HDMI.


Dolby Digital is always lossy. Blu-ray still supports Dolby Digital and DTS, but it also supports Dolby Digital Plus (a more advanced lossy format), DTS-HD High Resolution (also a more advanced lossy format), Dolby TrueHD (a lossless format that has its roots in MLP - just like DVD-Audio), DTS-HD Master Audio (also a lossless format), and uncompressed multichannel PCM. Any of these can be included on Blu-ray.


It depends on how the player is configured. If the player supports on-board decoding (as pretty much all current players do), you can set the player up to always output LPCM. You can also set the player to output a bitstream, though.