I've had an experience with imbalance and it was a result of listening to iems with a defect in one of the drivers. I think my auditory system gotten used to the imbalane and whatever I switched to sounded shifted center. After I listened to properly balanced set for a duration, I don't notice the imbalance from the same earphones.
I need to get a proper hearing test. The audiologist I've been seeing only tested practical hearing up to 8k. But, the imbalance in some parts were apparent.
Question. If you live with an imbalance, doesn't the brain get used to it, and you lose a sense of imbalance over time? I guess this pertains to a degree of imbalance.