I agree the definition of "Soul" in reproduced music may vary to the listeners mileage.
To me a system with soul is when the reproduction of music is so real, it moves you1
Saturntube,
The wold real is even more dangerous than soul in sound reproduction. Any one knows that reality can not be fully reproduced by two speakers in stereo. You have to rely on a number of clues that make you remember reality and also have a system that does not add any type on interference that immediately outclasses it, destroying your enjoyment and pleasantness. The emotional factor, (it moves you), can play an important role in it.