First and most importantly, your speakers should be on the long wall, not the short one. This will stop the problem. Why we naturally think speakers should be deep in the room on the short wall always fascinated me… we all just thing think this is the correct thing to do.
Notice what you have already done… you toed the speakers inward. The reason they sound better is not because the speaker is “firing at you” but because you are limiting the damage the side walls are causing. As the speakers try to fire sideways, those soundwaves bounce off the side walls and given the delay (echo) is so short, they interfere with your brain’s ability to interpret locality. By toeing in, you are lessening the amount of energy bouncing from those side walls.
When you put your speakers on the long wall, the time delay from bouncing off the sides is extended… delay starts becoming echo… now another psycho-acoustic effect comes into play, the Haas Effect… this actually helps your brain localize information from the main source, the speakers (which contain information from the recording etc. etc…)
With your speakers on the long wall, you may actually feel they sound better pointing straight out because you will (may) want the longer-delayed reflections because of the improved imaging this will cause. (Also look up “stochastic interference”… the introduction of noise to enhance perception… the delayed sound waves are a type of noise.)
If you must put your speakers on the short wall, try placing sound absorbing material on the side walls… just assume there is a mirror on the side walls… so from your chair, where the mirror allows you to see the speaker, put a panel there. You can get really cool stuff from a guitar/music store that sells recording equipment.
I learned all of this from owning Magnepans… a dipole radiator. The rear firing sound bounces off the back, then side walls and creates a longer and mixed time delay that fills the room with “noise” and from the Haas Effect, makes scary good imaging. It is addicting. Now the lower frequecies can get cancelled out and that is a whole other problem…
Bruce in Philly