I dont think you need to change components, a square room makes it hard to dial in soundstage and imaging. You may need some absorbion panels and I would start with bass traps in the corners behind the speakers.
Experiment with quilts, blankets, and pillows in the corners. As you stated, the large bass drivers may be affecting the image.
In my room, 12' x 16', placing thick absorption panels in the corners facing the speakers helped shape the soundstage and gave clarity to the vocals.