This has pretty much been answered, but I'll explain it a different way.
On this chart, the blue bars represent the dB level of each speaker as measured from the listening position with no correction or calibration applied in the receiver. The orange bars represent the amount of correction applied in the receiver during the calibration process in order to get the speakers to the same level (again, as measured from the listening position). The thin horizontal line at the top of the graph represents the "reference level" to which the speakers were calibrated.
Let's say that the sub was set to 10 (like yours is) in order to get it to the reference level. The other speakers needed different levels of correction -- some more, some less -- as you can see. These correction levels are stored in your receiver and allow the receiver to give each channel the proper level of signal so that they play at the same loudness relative to each other, regardless of the master volume setting.
Any clearer, or did I make it worse?
