When I was building my personal theater I auditioned different speakers because I wanted to create a true reference one. M&K speakers are for sure the perfect solution if you are looking for a reference cinematic experience.
Dynamics are incredible, voicing is neutral, bass is powerful and when the tweeter kicks in the tonal balance remains perfect. S150 when coupled with X12 subs are perfect and all the speakers literally disappear in the theater giving a great sense of realism to the image.
Subs are incredible, tight bass, controlled and quick response, power to share. They are amazing when they explode in such a controlled manner. Placed correctly they will offer a quasianechoic response and pressurize the theater with infra-sonic spl that is a joy to feel.