I’ve been pondering the harman curve this morning, or more specifically why the convention is to measure headphones with references to the harman curve, but to measure loudspeakers with reference to an ideal flat response. Perhaps for professional monitoring a flat loudspeaker response is ideal, but if Harman found that users prefer a non linear frequency response in a headphone, is there any research that suggests a similar preference for non linear frequency response in speakers and if so why is that not the reference for non professional loudspeakers?