Have you tried the contour switch on the back of the headrush? It is designed to dampen some of the boominess, hopefully enough to make it bearable.
Other than that I would first advise to never tweak profiles with headphones and always do so at gig levels. After that? Buy a better speaker before you go adding an external EQ. I've had good luck with EV ZLX's at just $100 more. GL