The difference is whether or not you are looking at in-room or anechoic response. The marketing literature spec of 122db includes room gain that can add 11-14db to the anechoic response. To keep distortion in check the DSP limits output at those max levels.
At max output near 108db anechoic, and just before the limiter kicks in, distortion is fairly high at -10db down from the fundamental from 45-100hz. Also at max. output, in the 20-40hz zone distortion is around -20db down. As you back off max output to say 100db or 112db in room, distortion falls off dramatically to around -35db down from the fundamental. 112db in room is very loud.
