Looking for new speakers for large audio room

shawarma, what is the ceiling height? That is certainly a larger room.
To get real low end in a room that size you will need at least four 15" subwoofer drivers. You would need Trios and subwoofers.
8 or 9 foot (depends on ceiling height) Sound Labs with four 15" subwoofers will work but that is pushing you price limits. Magneplanar 20.7s will work well unless you like listening above 95 dB. You could afford those and subwoofers. Line source speakers work better in larger rooms. Their volume does not drop off as fast with distance.

Edit: ceiling height is 2.8 meters in height

using two REL S/812 woofers in my set up

I have auditioned the Magnepan 30.7 but my pass labs XA 60.8 amp isn’t powerful enough to drive them loud enough in my listening room

what about trading out your subwoofers and getting something like a pair of Perlisten d215s's.  Given the size of the room, that might resolve the issue you are having.  

Add a couple 15" to 18" subwoofers. Spread the subs around to get better coverage.

Try to audition one of the larger Legacy speakers. Even their largest will be easily driven by your Pass amp.