Excepting hearing loss or unmatched tubes, the most common reason not to use a centered balance control is if your room’s rear or side walls are not symmetric with regard to placement of your speakers. This also happens if one side wall has openings, or is more absorbing than the other for some reason. The central image will shift to that side as there are stronger speaker reflections from the opposite side wall.
While you can use a balance control to offset this, it still never really sounds quite right because the reverbarent fields of the left and right speakers are different even though the apparent volumes have been equalized. You also can see this difference if you use measurement programs like REW.
One other way to deal with this is to use a moveable reflective surface near the speaker on the problem wall if room layout/decor is the problem.
While you can use a balance control to offset this, it still never really sounds quite right because the reverbarent fields of the left and right speakers are different even though the apparent volumes have been equalized. You also can see this difference if you use measurement programs like REW.
One other way to deal with this is to use a moveable reflective surface near the speaker on the problem wall if room layout/decor is the problem.