Just saw this over on REG's forum:
"In a previous set of remarks, I mentioned that one could
see the clean sound of the Harbeths(the good materials
behavior) on measurements. And it occurred to me that I
should mention what these measurements are.
One way to see it is to measure the mid driver by itself
and look at its behavior out of band(at the top).
It has a very clean roll-off, remaining smooth all the way down.
Most drivers begin to have misbehavior of a more or less
aggressive nature, which is suppressed in level by the crossover roll-off but is even so there.
A second thing(which is related closely actually), is that
if one looks at the "waterfall"(eg in the Stereophile
measurements of the M40.1s
figure 7 you will see that the region of maximum hearing sensitivity (3-6kHz) is extremely free of grundge.
I invite you to compare this, for example, to the same region in the Wilson MAXX Series 3 (p 71, figure 8 of the current[Septemeber} Stereophile) to take a random example that is on my mind because the issue just arrived."
I haven't received my 09/09 issue, do the MAXX 3s have a problem in the 3-6kHz region?