Have you demoed any KEF KHT-systems? They often do a real good job of filling small/medium sized rooms with sound and are easy to integrate, and naturally - have a really excellent sound for their size, often times very thrilling infact (think KHT-3005SE). I've heard the Boston Acoustic Sound Ware XS 5.1 at a dealer in a smaller room once and it too faired well. A friend of mine owns the QAcoustic 2000 system and it's impressive. He's got a similar sized room as yours. But as always - having a trial in your own home is often key to determin if that speakersystem works or not. It's not always down to the size of the room, but also the acoustics of the room, and how you place the speakers.