I think the 'copious amounts of treble energy' comment belongs to me. It's a characteristic of compression horn tweeters because of design and efficiency they can put out life-like levels of undistorted treble that makes other tweeters sound compressed and lifeless. The fatigue-inducing treble you describe is different and results from distortion. The level of the DF tweeter can be adjusted by the value of the resistor to suit the environment.
Brian
Take control! DIY.