DxOmark testing for the Sony RX100 shows best image quality at "manufacturer ISO 80". However, the camera defaults to ISO 125 and will not choose an ISO less than 125 in auto ISO mode when shooting in the brightest sunlight. The RX100 manual specifically states: "When [ISO] is set to a value lower than ISO 125, the range for recordable subject brightness (dynamic range) may decrease", which strongly suggests that the base ISO is manufacturer ISO 125.
What is the true base ISO for this camera?
I also see that DP review gives better Dynamic Range @ISO125 than @ISO80, completely different as DXOMark ?!
What is thet best ISO to obtain best DR, please ?!