To be clear, you tested the components by switching the places of the left and right speakers and the image still skewed to the same side? Speaker imbalances/difference are apt to be more significant than any electrical component. I also presume you tested the overall electrical balance of your system by switching the speaker leads from the amp going to your speakers?
If it is truly room issue, the easiest fix is to use the balance control--just leave it at the 1:30 position--that is what the control is designed to do. I am amazed how many listeners do without a balance control, I find it essential.
The other way balance can be restored is to move one speaker forward by a small amount (I would work with 1/2 inch increments). The closer a speaker gets, the more the image shifts toward that speaker because of higher volume (less fall off of volume because of distance) and because, of a timing change (your brain will interpret the sound coming first from the nearer speaker as an image shift in that direction). I personally don't like skewing the image position a lot by making such a position change, so again, I prefer to just use the balance control.
It is always productive to try changes in speaker placement and placement of your listening chair. But, when doing this, keep in mind that there are other considerations than getting the image to center correctly. Be sure to get the balance of bass frequencies correct and avoid positions that cause sound to wildly change when you make minute changes in your listening position.
Trying to treat the room to cure this problem will not be easy to do. If there is an imbalance in sound arriving from one direction, a big compensating change to absorb some of that energy to "balance" the room will inevitably create tonal changes because it is nearly impossible to uniformly absorb sound energy across all frequencies. The result of such treatment is unpredictable. But, if the problem has to do with standing waves and other such forms of constructive and destructive interference of waves, some treatment, such as bass traps in the corners could be helpful. I would also also try very modest wall treatments, such as putting tapestries on walls, before going wild with specialized room treatments.
Finally, I note that your speakers are quite far apart for your listening position. Even if you toe them in to face much more directly at your listening position, it would be hard to get a very solid sounding middle. If possible, you should at least try moving the speakers much closer together.
Good luck on your experiments.
If it is truly room issue, the easiest fix is to use the balance control--just leave it at the 1:30 position--that is what the control is designed to do. I am amazed how many listeners do without a balance control, I find it essential.
The other way balance can be restored is to move one speaker forward by a small amount (I would work with 1/2 inch increments). The closer a speaker gets, the more the image shifts toward that speaker because of higher volume (less fall off of volume because of distance) and because, of a timing change (your brain will interpret the sound coming first from the nearer speaker as an image shift in that direction). I personally don't like skewing the image position a lot by making such a position change, so again, I prefer to just use the balance control.
It is always productive to try changes in speaker placement and placement of your listening chair. But, when doing this, keep in mind that there are other considerations than getting the image to center correctly. Be sure to get the balance of bass frequencies correct and avoid positions that cause sound to wildly change when you make minute changes in your listening position.
Trying to treat the room to cure this problem will not be easy to do. If there is an imbalance in sound arriving from one direction, a big compensating change to absorb some of that energy to "balance" the room will inevitably create tonal changes because it is nearly impossible to uniformly absorb sound energy across all frequencies. The result of such treatment is unpredictable. But, if the problem has to do with standing waves and other such forms of constructive and destructive interference of waves, some treatment, such as bass traps in the corners could be helpful. I would also also try very modest wall treatments, such as putting tapestries on walls, before going wild with specialized room treatments.
Finally, I note that your speakers are quite far apart for your listening position. Even if you toe them in to face much more directly at your listening position, it would be hard to get a very solid sounding middle. If possible, you should at least try moving the speakers much closer together.
Good luck on your experiments.