@rauliruegas do you not prefer the character of your main speakers (in the upper sub bass region) to the character of your subs?
I find that if my subs roll in any higher than 40hz for general listening, 44hz for 90's electronica or a maximum of 54hz for some dub reggae, there is a sense that the subs are treading on my Focal's toes in a way that thickens the bass and is less articulate, and generates less slam.
The alternative for me would be to swap out my Velodynes for Focal sub Utopias, but two things prevent this. One is the cost, since the sub utopias are passive id have to invest in some serious amplification, especially as I'm about to add a third pair of dd18+, and the other is the disappointing on paper frequency response of the focal subs, they arent really rated much lower than the same field coil bass drivers in the Stellas. I've got used to a system that is flat to 15hz, and having lived with that i have no desire to go back