Funny you mention Magico, I'm going to be checking out the Magico A3 speakers soon.
I tried hooking up my JL subs in the REL fashion (they allow for that type of set up) and didn't have great success - the sound got tonally darker and less dynamic for whatever reason. So I went whole hog and bought a high end JL crossover to "do subs right" and split the signal between the mains and the sub (as all the subwoofer aficionados will tell you).
But it's such a friggin' hassle I can't get around to doing it.