@ssmaudio To actually answer your question, the bass issue would depend on your room and where you decide to position (or have to position) the speakers. Also, remember that larger speakers that need some kind of stand to lift them a little off the floor can have a lot more internal volume than many small floorstanders. I suppose technically the LS 5/8 is a monitor, but it doesn't conform to our usual modern understanding of that term. The REL's you have are good subs, so to my mind this is a non-issue. Get the best sounding speaker you can, then worry about lower-end bass later.
BTW, that recommendation for QLN a few posts ago is an interesting one. They were very high on my "try to hear" list, and I have every reason to believe they would be very good.
https://parttimeaudiophile.com/2020/05/15/qln-prestige-three-loudspeaker-review/
BTW, that recommendation for QLN a few posts ago is an interesting one. They were very high on my "try to hear" list, and I have every reason to believe they would be very good.
https://parttimeaudiophile.com/2020/05/15/qln-prestige-three-loudspeaker-review/