I'm curious,what exactly about the sound are you trying to improve?
Is your room properly treated?
If the rooms Acoustics are sorted out,with those speakers,I think I would be looking at an amplifier upgrade before moving on from the ProAc's...
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?