Introduction
I found a frequency response measurement of the HE400i that is more accurate than the ones I previously used in my equalizer settings. I discovered a way to extract the graph data from Rtings.com. Rtings.com has measurements of lots of headphones, and their methodology is one of the most accurate. So, I imported their data into Room EQ Wizard and created an equalizer profile to correct the frequency response of my HiFiMan HE400i.
Measurements and Correction
I came up with the filters manually. I’m choosing not to boost the troughs or over-correct the treble to prevent side effects that arise when any particular listener’s ears don’t exactly match this graph.