What I gather from a review of your speakers is that the low frequency driver is crossed over @ 150Hz (no slope mentioned) and it's compartmentalized and rear ported).
Not certain if you have one or two REL's, but regardless it would seem that you have a "sort of" subwoofer "swarm" taking place (with two of the subs being rear ported).
Aside from the square room (really bad) it may sound OK if you can place the speakers in a diagonal placement (room corner between the speakers) as already mentioned by russ69.
If not I would just pop for a pair of nice standmounts (like the new Harbeth P3 - ideally placed on the diagonal) and blend in the REL(s).
DeKay
Not certain if you have one or two REL's, but regardless it would seem that you have a "sort of" subwoofer "swarm" taking place (with two of the subs being rear ported).
Aside from the square room (really bad) it may sound OK if you can place the speakers in a diagonal placement (room corner between the speakers) as already mentioned by russ69.
If not I would just pop for a pair of nice standmounts (like the new Harbeth P3 - ideally placed on the diagonal) and blend in the REL(s).
DeKay