Hi Peter,
I am using a pair of Watts/Puppies 5 in a room half the size of yours with excellent results. I get plenty of bass with the smaller Watts/Puppies 5 most of the time. I miss the deep bass only in a few specific recordings.
A few things you may want to consider before taking the plunge with the larger, better, and more expensive Maxx.
1. Try moving your speakers around a little (or a lot). You may be surprised how a small change can alter the bass response, in quality and volume.
2. Try changing the speaker cables. When I switched from the recommended MIT CVT to a triple run of inexpensive OCOS, the bass improved noticeably in quantity and tightness. If you have a spare amp, it might be worth a try as well. The bass output of my Watts/Puppies 5 increases when I switched from Rowland Model 7s to the BAT VK-60s, and finally to a digital switching amp, which seemed to have doubled the bass output, subjectibvely. Of course this is also an expensive option, though far less than the cost of a pair of the Maxx.
3. Have you considered a subwoofer? Wait, don't cringe. I had great results with a Muse 16 with special crossover card to match the Watts/Puppies 5. The sound was nearly seamless. Now, my Velodyne DD-15 (15-inch woofer with servo-control and 1000+ watt digital amp) doubles as my video AND audio subwoofer. This subwoofer is pretty amazing: it is small, powerful, and ultra-fast. With the on-screen digital adjustment and a supplied microphone, I am able to customize a nearly seamless blend with the Watts/Puppies 5 at a fraction of the cost of "audiophile" subs. The bass increase in depth and volume is nothing short of staggering. You can also go to the larger DD-18 to move even more air. I prefer the smaller, faster, and definitely cheaper DD-15.
Speakers' bass response in a room is position dependent, amplifier/cable dependent and difficult to predict. Try the above options if you can. But if you must have the Maxx, it would be ideal if you could try them in your room first.
