Just having a nosey around you tube and found this vid using pink noise to balance track levels. The idea is not to balance tracks against each other with the fluctuating dynamics and therefore fluctuating levels but to use pink noise as a steady level reference instead. The final outcome sounds pretty good with each instrument being presented fairly and not drowned out by another. It appears to be an old idea but I never heard of it or seen it in the forums and for that reason here it is.
This guy uses hearing to balance but there's another vid where another guy uses an output meter for the pink noise and another meter for the track db level.