Best Subwoofer To Use With A Two Way Speaker System

I have the Wilson Benesch Arcs and I pair them with a REL Strata III, picked up on CL for $400. Great combo, easy to dial in, and they blend together well so the REL isn't intrusive.  Sounds like I have floorstanders instead of monitors, but without overpowering the room.

I'm using a JL Audio E110 sub with the 2 way Lawrence Violin SE speakers. My Primaluna Int amp has only a mono sub output but it is more than enough in my 13 x 18 room. Since the speakers go down to 38hz, my dealer suggested I run the speakers at full range and crossover the sub at 45Hz. Both the speakers and subs are about 48" from the front wall. I was told to invert the speaker wire and adjust the phase on the sub until there was a null in the bass. I switched the speaker wires back to normal and then adjusted the volume on the sub to where it can't be hardly heard and doesn't overwhelm the sound of the speakers. As a result the bass is tight and no boom. If your room is larger you might consider the E112 or 2 E110.

JL subs are known speed and clean sound.  Check out the online and magazine reviews

Ive had very good luck with REL.  A pair of Subs has worked far better than one.

I have a pair of REL Strata IIIS with Decapos. Agree with Chlv0ter, adding a 2nd sub was as significant as adding the 1st one and not just for bass performance but overall smoothness, dynamics and clarity, just more musically convincing. These RELS integrate so seamlessly, they never impose as I have heard with other sub systems.

If I had the room to add a 2nd REL and could locate one in my area, I'd definitely try it.   I believe in what the commenters say above - what one does well, two likely do better.   It's not happening in my 11x10 room, but if I had the space for it I'd love to hear what a 2nd REL would do for the sound.