It doesn't sound as spicy in the treble as it looks because past 3kHz, the peaks and valleys of the IEM are roughly matching up to the valleys and peaks of the average person's sensitivity to sound. Look up equal loudness contours; the frequency response of the human ear, if you'd prefer that explanation. 2-3kHz is still solidly in the speech range and that's typically perceived as 'shouty' rather than 'sharp'. Whether intentional or accidental is always hard to tell with Chi-fi, but 7Hz has made good sets before, so...
