M&K may be a good choice for subwoofer if you have a higher budget. When it comes to subwoofers, Adire Audio can slay other brand names at it's price range without even breaking a sweat. In a side by side comparison, Adire's Shiva will have other brands like Paradigm, Polk, Infinity and JBL run away like a dog with it's tale tugged between the legs.

I've listened to my friend's Klipsch subwoofer costing $1,000 and my Adire's Shiva out performs it. I spent less than half of that. Its tight, loud, musical and the ability to move the air is incredible. Check out www.adireaudio.com for more detailed spec on their drivers. Shiva has Xmax distance of 15.8 mm one way! That's the amount of air it can move/vibrate. I doubt you'll find drivers like that from $500 subwoofer if they even list it in their spec. 1 Adire's Shiva may do the job for your large room. Why spend more on getting two? What about the square footage that you are giving up by having two? If you think Shiva may not be enough then you may want to try Adire's 15" Tempest or the ultimate Tumult (Xmax = 34 mm one way). These products can be delivered to your door and dollar for dollar, the quality is outstanding. I'm not their salesman. I'm just a fortunate user of their product.