I use a Rythmic 15 in sealed sub. I high pass the mains at 50 Hz and set the sub crossover to 50 Hz. May old ProAc monitors are "rated" to 27 Hz at -3db. The integration is seamless and the bass is tight and "musical." IME it is challenging to integrate a sub w/o high passing the mains. The Rythmic gives you a lot of control including a parametric EQ. If you have the $$ two may be great with your Cornwalls.
Add a subwoofer?
I run a pair of Cornwall 1’s driven by primaluna, VPI, and Sutherland 20/20. Room is 34 x14 x 14 high. I love the Klipsch, but never felt like they were overly heavy bass. I’m curious about a subs ability to “fill in” the sound. I called a dealer regarding REL’s smaller products. I was told that the Cornwall has huge bass and I’d need a very large sub to notice a difference. Really can’t afford a quality big subwoofer. ie thousands of dollars. Not wanting thumping bass, just fuller sound. No experience with subwoofers so, ,,,,
Thanks for your input.