JH, defining a "higher pitch" is somewhat subjective. My thought would be to first try the 2.5KHz band on your equalizer, but experiment with different bands or combinations of bands to see if you can get an improved result.

Another thought would be to use the "Front" setting on the auto-equalizer to attempt to adjust the other speakers to conform to the mains, if you haven't already tried this.

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Enjoy the music, not the equipment.