At least it sounds like your room isn't just a concrete cube, and it opens into another space. If you weren't aware, a set of parallel walls will set up standing waves at a particular frequency depending on the distance between them (notice how the two largest surfaces of Axiom speakers are non-parallel). This makes the reproduction of smooth even bass around those frequencies created by the height, width, and depth of the room more difficult. When a room has more than one pair of walls the same distance apart the effect is multiplied.
If you wish to get the most out of that room, an investment in some sort of bass trapping may be worth while.
