Looking for new speakers for large audio room

sorry 'bout the double post.....I did not think the 1st one went thru.

@ronboco it does, but potentially to an even higher degree as you have elevation in the mix. Also, and is recommended, the crossovers of each are slightly different. Take a look. It’s an expensive endeavor with the Rels though, and the S serie subs are designed specifically for this application. They work fine as singular subs but they are setup to daisy to one another and have mounting plates to tie them together as one. Shocking set up. It is a similar tactic used in live shows where line arrays are pretty much the norm.

Dutch and Dutch 8C. Half of that price range but will beat most. 

But you seem to be just right for Grimm LS1be. Those are endgame speakers. 
https://www.grimmaudio.com/hifi-products/loudspeakers/ls1be/

Time to outgrow all the puerile preamp, DAC, amp banter. 

@shawarma
In your large space, are you satisfied with the Avantgarde uno sound with the exception of bass impact?

You really should keep those wonderful speakers and only add what your room is missing which is several subwoofers to properly pressurise that large of a room.  Most any new speakers you might purchase would still need those subwoofers due to the room size.  My main listening room is that large and I wasted time and money upgrading to larger speakers when in the end several subwoofers were the only thing that could properly pressurise my room.  Wishing you the best.