Subwoofer for Kef LS50 Wireless II?

Hello, I own two Rel T9’s. With the Speakon connections they sound really good. The store in the Chicagoland area has both of the new KEF subwoofers.
https://holmaudio.com/
 They both claim to play down to 11hz at -3bd, but the bigger one which is the KF92 plays at 110 db and the little one which is the KC62 plays at 105 db. Since my system has the sub outs not being used and the KEF has a wireless kit I thought it might be good to integrate it to play from 11hz to 30hz which my RELs are missing. 
I don’t know if this will work but the store listed above let’s me try before I buy. I tried to borrow the bigger one last week but it was out on loan. These subs are so popular now. It wasn’t a total waste since I borrowed a power cord to demo. 11hz is really low. Does music even go down that far?  I hope this gave you some ideas to try since I am going through the same thing.

thanks for the feedback
i think ive been convinced to stay the course with this sub a while longer
i just ordered a subddude
also just heard a very good bass track , Tidal MQA version of Cardi B's Bodak Yellow, this is the first track that this sub has impressed me with, interestingly enough this particularly track it does not rattle my house

the KC62 is a killer sub considering size and $$. Its worth a look.

A new review by Herb and Stereophile

https://www.stereophile.com/content/gramophone-dreams-49-kef-kc62-subwoofer

I reading this thread with great interest.  I have an SVS SB2000 Pro and was wondering about how a set of the wireless ll’s would would sound with it.

JD

update,I now have the KC62, long story short, perfect marriage
integration took seconds with the app, set it and forget it, no looking back
trying to resist the urge to purchase a second unit
it does not have the output capability of the SVS
app control on both units is superb, I'll never do subs again without app control, no going back, I read a blurb somewhere that both JL Audio and Velodyne will be releasing new app controlled products

the KEF's with the KC62 for the right room and music preferances is without a doubt a killer killer value in the world of two channel
the whole system is just set it and forget it excellence, I'll stop short of calling it endgame but it ticks a good many of those endgame boxes