Have you placed the subwoofer at the listening position then walked the room listening for the loudest bass mode?
Different brand/model Sub(s) integration
I have an all analog setup, the speakers are 2 Tannoy Kensington and one REL s/510.
I have a room mode at around 30Hz, that I can't fix regardless the REL's location. The only viable solution I can see is to add another sub, because the REL does not have DSP and no bass-trap can effectively absorb it.
Do I need to add another s/510 or I would be better off adding another brand with DSP so I can null the room mode?