For separate controls, maybe a Redgum? I think all those have separate pots, but not sure if they are synchronized or not.
Some balance control options that come to mind are Accuphase, Luxman, Naim Supernait, Manley Stingray.
Some balance control options that come to mind are Accuphase, Luxman, Naim Supernait, Manley Stingray.