With all channel trims at 0, a -30dB setting on the 975 volume control produces a 75dB test tone from the 975.
Sounds good. About the same for me.
The same -30dB volume setting produces a 60dB test tone from the Disney WoW Blu-ray.
That's right. Those signals are recorded at -20dBFS, so to get them to 85 dB SPL (Reference Level), the volume would be set to -5. That is very loud, so I normally back it down 10-15 dB below reference.