@OP - If you like the Response D2, why not listen to the Response D20. I used a pair of Proac 2.5s in a room smaller than that for many years with excellent results. BTW, in a room that size you need some diffusion as well as bass trapping. I would see to that before changing speakers.
Upgrade from ProAc Response D2 in small room
I’ve been enjoying my ProAc Response D2s, supplemented by a pair of tiny REL subs but…of course wondering if I can improve. The room is a bit small: 10' 4" x 14' 6" x 8 and treated with several GIK bass traps. Speakers are being driven by a Belles Signature Dual Mono.
Any thoughts on possible upgrades?