I'd suggest following Davt's lead and look at your room configuration. Asymmetry can be a problem, especially with speakers that have a wide dispersion in rooms where the primary reflection points are different from the left side to the right. That can really skew the stereo image.
If that's the source of your problem it can often be improved by experimenting with speaker placement in the room and acoustic treatments.
If that's the source of your problem it can often be improved by experimenting with speaker placement in the room and acoustic treatments.