I think that it would be best in your small room to get some decent stands for your monitors and to use a single Titan II LE. I own an ACI Titan II LE, and it works very well in my ~13.5'x~18' living room.
It is best, of course, to place a subwoofer in an acoustically optimum position. However, due to room layout and aesthetic constraints, I can not place the subwoofer in an optimal position in my living room. Instead, it is about 3' to the front and to the right of my Vandersteen 1C's, yet the ACI Titan II LE still does a virtual disappearing act, seamlessly integrating into the Vandys' soundstage. A large REL should function with similar success (but for *much* more money), but few other subwoofers I've heard would be up to the challenge.
Incidentally, the helpful folks at ACI have a newer, somewhat smaller subwoofer out that they call the Force. I haven't heard it, but the Force is reputed to sound and function very much like a less powerful Titan II. It is still probably too large to allow its more optimal placement within my living room, but it is another option to consider.