I have 3.6's in a 12x15 room. You should be ok in that room and with that amp
It really comes down to how you are using that room... if it's a dedicated audio room with very little of anything else, then I bet it would sound fantastic with a bit of acoustic treatment. If you need to fit lot of furniture in the room as well, then I would think it could be difficult to get enough space behind the speakers. Maggies really need room behind them to breath....
Your room size may not be optimum, but there's no reason you can't use Maggies in it.
If you have to place the Maggies close to the wall behind them (like less than 3 or 4 feet out), I suggest either diffusing or (only as a last resort) absorbing the backwave. You REALLY don't want to overdo absorption - much of the magic of a good dipole is the extra reverberant energy the backwave adds, and you want it to be full-spectrum energy, just like at a live performance.
If it's your mancave, you might even try a diagonal or semi-diagonal placement, the latter really staggers the distances to room boundaries.
dealer/manufacturer/longtime Maggie fan
My MG12's do their thing(mains, in a bi-amped system) in an 11X13X8 space. It's all about room treatment & placement(you and them). YES- diffusers behind them, if they're close to the wall. One nice thing: you don't have to worry much about side reflections(with Maggies). I listen at levels that approximate those found in live(Jazz/Blues) venues. Once upon a time; I was able to overload the room with a pair of small monitors and a Dynaco ST-70(WELL- There WAS a bed in there too......).