Hmmm...
0 db may be "reference level" volume...
It could have something to do with what your receiver set the individual channel decibel levels to, of the speakers that are connected to it...
For example...
My front speaker channels are set to -3.5 db when I run MCACC (Pioneer's room correction software)
With the front speaker channels set to -3.5 db, I can turn the volume level on the receiver to +12 db max...
When I set the front speaker channels to +10 db, I can only turn the volume level on the receiver to +2 db max...
The higher the speaker channel dB level, the less you can crank the overall volume of the receiver to...
Hope that makes some sense...
