Your space is about the same size as mine and mine is open to the rest of the house. I use a single EP600v2 and it doesn't even break a sweat. To reach the 75dB calibration level for my area, I barely have to nudge the gain knob on the EP600. There's a ton of headroom to please any basshead. The one thing I will say about the EP600v2 though is it's very linear down to about 20Hz. Don't be expecting any mid-bass emphasis like other subs. It will play what you put into it and nothing more or less.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated