I have experienced the exact same problem as you in pretty much the same size room! A number of fixes for me. First, I discovered that one speaker was about 2db louder (near cone measurement), I replaced some tubes to equalize output. Second, speaker placement, front to back, side to side, and amount of toe in all effect this to some extent. Third, room treatments can make a large difference as well, something like an echobuster at your first reflection point on your wall should help (curtains may help some as well).
Goinbroke makes an interesting observation in that it as much the lack of reinforcement on the speaker in the open area that is part of the problem. Some sort of free standing combination absorber/reflector at first reflection point might help. I plan on experimenting with this as well. In the meantime there are times when I still have to use the balance control.
Goinbroke makes an interesting observation in that it as much the lack of reinforcement on the speaker in the open area that is part of the problem. Some sort of free standing combination absorber/reflector at first reflection point might help. I plan on experimenting with this as well. In the meantime there are times when I still have to use the balance control.