Going backwards: what speakers best match a pair of REL s/510s

I’ve recently purchased a pair of REL s/510 subs that are amazingly musical. They seem perfectly matched with my bookshelf speakers, the long-discontinued Platinum Reference 1 (specs: https://audio-database.com/PLATINUM/speaker/reference1-e.html; reviews: http://www.audioreview.com/product/speakers/floorstanding-speakers/platinum-audio/reference-i.html). But as we all know in this hobby perfect is never good enough. I am wondering if another matching might produce even more distinctive separation of instruments within a deep soundstage and the sense of live in-the-room performance that is produced by the pairing of the Platinums and RELs. Am I crazy, or is another level of nirvana reachable below the $15k/pair price point for the main speakers?

My system is McIntosh C2200/MC2102 tube pre/amp and MEN220 room correction with active crossover, Basis 2001 turntable with Hana ML cart (to be upgraded soon), Whest PS.40RDT phono stage, and Tara Labs Air cables and interconnects. The main speakers are 6' from the back wall, 3' from the side wall, in a 15 1/2' x 23' room with a vaunted ceiling that rises from 10 to 15'.