I noted that the 975 has a 90db range of sound which starts at -90 db and goes to 0 db. As noted before if you jack the signal to one speaker it decreases the available headroom by the amount of boost. I ran my Onkyo all the way down to -81.5 db and I am pretty sure it goes up to +18 db for an overall range of 100 db. Below about -50db the audio is essentially muted to my ears. At my midpoint -32db the audio is clearly discernable. Maybe it is possible to shift the midpoint on the 975 to increase the max output via a firmware update but it could be a hardware limitation based on output voltage.