Tom, yes I'd say that your description of Dynamic EQ, which I always use(I never need the volume compression of Dynamic Volume), and the RLO setting for it is substantially correct. When the system is correctly calibrated at 0, using a lower volume setting such as -10 would result in slightly lower apparent bass and treble response and less surround effect. Dynamic EQ corrects for this by slightly increasing bass and treble at lower levels and also making the surrounds slightly louder at those levels.
The RLO setting should be left at the 0 default if the material being played has about the same volume level characteristics at which movies are supposed to be produced. Some recordings of pop music aren't like that and are uniformly very loud with practically zero dynamics. That sort of stuff doesn't need the full DEQ lower volume correction for lower settings of the main volume control and it could be set at maybe 10 or even 15, but for well-recorded material leaving the setting at 0 should be satisfactory.
