I ran a test this weekend with the Digital Video Essentials disk and my system. According to the DVE docs the test tone should provide a SPL of 75 dB if the system is calibrated correctly.

With my 975 on max volume (0 dB) I read 71 dB at my listening position on the Radio Shack meter. My speakers have a senstivity of 87 dB. So it appears that with th volumen knob at 0 dB, which is unity gain, then the levels for HDMI appear close-for my system. I'll grant that it would be nice to have a little more gain for those with inefficient speakers or larger listening areas.