New 2012 MKX now @ 5000 miles. Love the car. Standard (not THX) sound system occasionally clips at moderately ( around half way on the volume indicator) loud music settings. It has not been consistent.
Replaced all factory speakers with much better Infinity Kappa Speakers this weekend, still have clipping (volume suddenly reduced on sharp peaks) basically the same as factory speakers.
Does this system have an independent amplifer separate from the head unit. I think there is a separate subwoofer amp, but the sub performance is not relevant to this issue.