That adds in the extra variable of how each individual listens to each source. Some here (like myself) listen to music through a DSP that matrixes the two channels to 5 or 6, while other listen in pure stereo (keep them nasty DSPs off my music!)

Then factor in what percentage of each user's listening is:
Stereo music in pure stereo, stereo music in 5.1, multichannel music, television viewing, movie viewing, etc.

Bren R.