The 975 does display DD 3/2.1 or 2/0, depending on the signal from the cable box. Night Mode is off.

Let me pop in a DVD here...the only music disc I can find is Alice in Chains Unplugged. (I'm testing with music content as it maintains a more consistent level than dialog.)

Even though it's a quieter acoustic performance, it's still averaging in the low 90s, with peaks around 95-96dB. So it seems pretty equivalent to the Blu-ray output.