Do you have anything to prevent reflections off of either wall. Some of the difference might be tamed by good room tunes.
Without having seen your arrangement it is impossible to answer accurately but the reflections off of the walls can cancel signals and alter your soundstage not to mention your frequency responce in that room.
Without having seen your arrangement it is impossible to answer accurately but the reflections off of the walls can cancel signals and alter your soundstage not to mention your frequency responce in that room.