Robert I measure the complex response of speaker which includes both magnitude and phase, not just the magnitude alone. ?I actual rely heavily on Group delay as one of my design analysis parameters. I also use step response as quick indicator of phase linearity. The DQ does credible job on both fronts which come as no surprise since they are both calculated from the impulse response. I believe that the acoustic phase which is represented by the summed pressure response is linear then the speaker is linear phase.?
I have also sent a separate private request for more information.?
Charlie Conger