I had the privilege of using a 1400 extensively as a prepro and I played with the YPAO settings a lot. Not once did I get an Out of phase on the tests. What surprises me is the subwoofer is a part of all the tests in the YPAO and the manual claims the YPAO sets parametric EQing to all the speakers selected. Upon running YPAO, my SW definitely felt less boomier and tighter, don't know how or why!