I have a pair of NX-Studios with an SVS subwoofer and surround speakers. My room is 13'x21' and is my family room, complete with lounge chairs, couch, 75" TV, baby grand piano, computer workstation (I work from home), etc. My point being, if it was a dedicated space for listening I think that would be big and maybe bigger speakers would work. As it is, the NX Studios work great and don't overwhelm the somewhat busy room. I'd love to hear the NX- big brothers but I'm quite content with what I have.
The NX Studios are the only pair I've ever built and they replaced a pair of B&W 805's, that I'm using for surrounds now.