Hi Alex, Are you sure the third order distortion measured is due to the headphone and not due to the measurement chassis vibrating. I've seen a wierd pattern on all innerfidelity charts of some tactile feeling headphone like Skullcandy crushers. If a driver breaks the thd needs to keep rising. But in those charts thd stabilizes down. Which leads me to believe that the measured distortion is more into the measurement system rattling than the headphone distorting. In a normal human head, this tactile sensation will be felt on the cheek through earpads. I care so less about "harmonic" distortion. Were you able to measure transient envelopes and intermodulation distortion? Also, I had earlier sent you mails regarding a different drive schematic for these if you were to be interested. Not sure if it reached you. Currently going through knowledge bases for a while now.