Those seem like really nice speakers but they bottom out at 40. [from website: 40Hz to 16kHz, ±3dB]
I have some speakers now that go down to 38 hz but the presence of just one REL sub does quite a lot, very noticeable, for the entire spectrum. I got that $1900 sub used for $900 and I am pretty convinced that a second sub is necessary. (Just waiting for a bit to see how some other things develop.)
Perhaps get a sub or two as a tryout and see what happens?
I have some speakers now that go down to 38 hz but the presence of just one REL sub does quite a lot, very noticeable, for the entire spectrum. I got that $1900 sub used for $900 and I am pretty convinced that a second sub is necessary. (Just waiting for a bit to see how some other things develop.)
Perhaps get a sub or two as a tryout and see what happens?