Turns on or off a hard-clipping saturation. This saturation occurs due to the integer precision of the original hardware, producing distortion inside the algorithm. This results in a more gritty/edgy/present reverb sound.
You need to have the LEV parameter above 160 before saturation is introduced. In the original hardware only Random Hall Ambience had the LEV parameter so those were the only algorithms with this type of saturation. In LX480, we have introduced the LEV parameter to the Hall and Plate/Room algorithms (and therefore the saturation effect too).
To get the original sound from the hardware set LEV to 160 (default) for those algorithms.