Had this issue.
switch the speakers, and listen
Left speaker is at an opening to a larger part of the house, right is in a corner, right always sounds. Better, it’s in a corner, where as the left loses some oomph to the stairwell, and open part of the house.
could just. Be acoustics. as mine is.
i switched the speakers so many damn times, but always the same,
i came to the conclusion it’s the “ROOM and acoustics”
not the amps, or speakers, cabling.
Just my my two cents