I know exactly what I like and that is a heavily treated (dead) room with a ruler flat response from 20Hz to 20KHz (16KHz is fine) relative to a slightly shallower Harman in-room target of -0.7dB/oct, constant 55 degree directivity and amplitude modulated distortion below -25dB.

The Heresy IV is mostly flat on-axis but exhibits very wide horizontal directivity; almost a constant 90 degrees. If your room is untreated, this will result in rather prominent high frequency content.