Cornwall IV and subwoofers

Anyone using Cornwall IV with subs?  If so, what brand and size? One or two? Ported or sealed? How are you connecting them? If line-in, what's your low-pass crossover point?  My goal is getting the best integration for music, not HT.

@wrm57 ,  FYI,  classic golden age jazz (50s-60s) is my favorite cup of tea.  And, the RELs really augment the lifelike sound that's present.  Surprisingly, even with 1950s recordings--they bolster the ambiance of the recording room.  I was playing Oscar Petersen's 1959 Porgy and Bess last night and the RELs do more than I would even expect on such old recordings. 
One more thing---

I think the Cornwall IV bass response is accurate where it exists. It's not bloated at all.  But, if you have a bigger room they may need help to pressurize it.  If you put these in a smallish room, I bet the bass end of things would sound larger than life.  My room is 15.' wide by 22' long with 10 foot ceilings.  It's big for me. 
I am. I have the Cornwalls on low (6") amp stands to get them slightly off the floor in my 13 x 22 listening room. I'm running a Pass 250.8 amp, PS audio DSD JR and Pass XP10 pre amp. I have a REL s510/SHO sub on high level inputs off the Pass amp and a pair of SVS PS3000 subs (sealed box, not ported) running off the pre amp outs on the XP10. I like them because of the mobile app interface and the ability to tune them via the app. I run them all so they come in around 60 hz or so and at a low volume. They all integrate really well. Te Cornwalls are great but lack the very deep bottom end. I also use Roon and Quboz and like Roon really mostly for it's parametric EQ functions. The Cornwall do have a tendency to have a bass boost in the 125k hz area or so, which I trim out with a deep notch filter adjustment on the Roon EQ. overall I'm pretty happy with the Cornwall - they're huge however- even bigger in person that what the measurements suggest! 
For me, and again for me... I have Heresy IV's with an SVS PB2000 pro. It's everything I need. The Heresy's with my Mac 240 are a sweet combination. The SVS gives every recording an easy weight and presence. I really like the SVS mobile app and pre-sets, really lets me dial everything in. Just my two bits..
I have the Cornwall 4’s in a 14x30 room with an SVS SB3000 sub. The sub fills in the bottom octave nicely. I never thought a sub was necessary until I actually tried it. Big improvement.