Having to deal with a small room after a move I pretty much have the same size as yours. I’ve had really good luck with the Reference 3a Reflector. It’s not a small speaker for a book shelf but I still run it with a pair of rel subs. I do turn the subs off sometimes for the hell of it. Sounds good with or without.
I’m using a 50 watt class A amp switching between kt120’s and 150’s. If you’re looking for an extra warm slow fuzzy slippers speaker this isn’t it. There is something special about a speaker with no crossover. The 3a is not bright it’s very natural with a big wide deep layered soundstage that goes beyond the outside boundaries of the speaker. It can make bad thin recordings sound better than they should. The best part it plays all types of music very well.
I rotate other speakers in but always crave that ref 3a sound, I tend to use these more than the other bookshelf’s.