I suggest you check out purrins CSD plots. Headphone decay is specific to different parts of the frequency range. Bass can decay slower than mids and treble and vice versa. Spots of problematic decay also show up ringing. Longer bass decay results not in sounding fast or slow or any of that ****, but muddiness and bloat.
Edited by Eternal Schism - 3/1/14 at 8:30pm