I have two magneplanar 3.7i speakers and am considering adding a pair of subwoofers as the room is large and the sound seems to be weak at the low end. Although the subs I am considering have low pass filters that are adjustable (JL Fathomf112 v2 12, Rel s/5 or s/3, Rythmik F12), I wonder if there is any benefit to limiting the frequencies going to the main speakers. As such, an electronic crossover would need to be interposed between the preamp and the amp. JL audio CR-1, Pass Labs XVR-1 are some of the boxes I have seen. But I don't want to add more boxes to the audio chain if the benefit is not audible. What opinions have any of you about this?