Apparently the full-range driver's waveguide increases gain and dispersion, while decreasing distortion, but it also inherently boosts midrange frequencies that must be tamed by the compensation circuit. My guess is that without the filter present you would have a non-linear shouting midrange response, but not necessarily cause damage.
But you will have to wait for one of the NuForce people to comment, who would know for sure if this is true or not.
Steve
