Obviously, an acoustic square wave is a discontinuity in pressure, which no speaker (piston) can produce.

As I see it, you are saying that the trained eye can readily detect speaker anomolies by examing the smearing at the transition areas in the measured output of the speakers when fed the proper signal. (I am a little fuzzy on how a triangle was related to "reproducing a square wave," however.)

Interesting. I'll buy that, but leave the discussion of what that means acoustically to others. ;)

Thanks.