You have it exactly right zhimbo.
I wonder how much if it is due to the drivers ability to produce complex wave forms. If I understand correctly, what we hear as notes from an instrument is a whole bunch of sine waves that have interacted with each other to form a complex wave form (or multiples thereof).
Here is an analogy. A pure tone is like a lake on a dead calm day. a single note is like that lake with first morning ripples. From there we can go up to an orchestra which would be like the lake during a major storm.
So, what I wonder is if some driver designs are just better at being able to reproduce all that complexity. If that is the case, you could have two speakers with identical frequency response graphs that sound quite different.
Enough babling for now.
