Neil,
Not all DVD players allow 24/96 to go out. Some will down sample 96k to 48k. Some will simply block it. Please double-check the user manual to make sure your player actually allow 24/96 digital out.
Also, which DVD did you play? Not all DVD contain 24/96 PCM track. Even if it does, you might need to select the right audio track from the DVD menu because 24/96 usually is not the default.
When you said "When I turn off Dolby Digital at the digital output, it defaults to D-PCM". I assume you meant changing a setting from the setup menu of the player, not from the DVD menu. If that is so, when you set it to D-PCM, it might be telling the DVD player to block Dolby Digital from digital out because if you are connecting to a regular DAC, Dolby Digital will cause loud noise and may damage your speaker. This is just my educated guess without knowing what player you are using.
Not all DVD players allow 24/96 to go out. Some will down sample 96k to 48k. Some will simply block it. Please double-check the user manual to make sure your player actually allow 24/96 digital out.
Also, which DVD did you play? Not all DVD contain 24/96 PCM track. Even if it does, you might need to select the right audio track from the DVD menu because 24/96 usually is not the default.
When you said "When I turn off Dolby Digital at the digital output, it defaults to D-PCM". I assume you meant changing a setting from the setup menu of the player, not from the DVD menu. If that is so, when you set it to D-PCM, it might be telling the DVD player to block Dolby Digital from digital out because if you are connecting to a regular DAC, Dolby Digital will cause loud noise and may damage your speaker. This is just my educated guess without knowing what player you are using.