Are there other ways to reduce those resonance or counter the effect of the resonance? Would more dampening work? Would grill on take away a bit of those peaks? Or would just a simple reduction of the treble knob smooth things out a little?
You have to test these things out but the point of these speakers is to either use them as they are or use EQ.
not really spend 500$ to make them behave better. Better spend that money on a MiniDSP device. Even the 2*4 cheapo could work for this.