Not all manufactures use the same number system for their volume controls. I would expect that when your system is set up to be optimal, "0" would represent reference level. With a meter, when setting up the speakers many people would look to set them to 80 - 85dB. This way when playing a movie, you should not have to go over 0 on the dial to get the best performance.
The reading on my DENON amp goes -50 to + ten is this d.b. level or what does it mean? At 0 on the volume control I can almost blow out my windows Also when I do a test tone and change the level of all speakers the volume really changes rite now I have all speakers at 0d.b. and center I have +2db . Also I just tried out a d.t.s. d.v.d. WAR OF THE WORLDS and had to bring down my SUB to -2 and center channel up 2 DBs . should one have to change the setting when you switch to d.t.s. I hope Dan the pro can answer this one happy days stewart