Um, maybe mine is unusual, but I did turn mine off. Page 3-46 of the owners manual, Dynamic Distortion Limiter. It can be disabled in the Radio. I did this and I can turn my headunit up as high as it will go and it will not turn off.
1) Turn the Radio off.
2) Press the on button and pushbutton #1 at the same time until the options menu is displayed
3) Press the Audio button until the correct option appears in the display
4) Turn the Audio nob to adjust the setting of the option
5) Push the Audio nob to select another option or press OFF to exit
PS- It's also accessible in the DIC as option "Audio Distortion Limiter", but it still turns off with that setting, just much higher.