The treble peak is near 14kHz, where people's hearing starts to drop off massively. Humans don't have good resolving power or pitch identification up there anyways, so it's not harmful. That 14kHz peak is a good reason why the HE400 has good air. The

FR/CSD differences are not huge, but the velour pads seem to indicate overall smoother response (less dip in upper mids, more gradual peak in treble, more gradual transition from bass to the upper mid recess). First plot is with the pleather. The second plot is with the velour pads.

I haven't heard them with the velours yet to confirm with my ears, but given the number of people who say that it works, and these measurements, it's a high probably that the velour pads do work.

Awesome, many thanks purrin. The measurements hold up very well with what my by-ear comparison between the two pads were.

That upper mids / lower treble raise by the velours is beautiful on the CSD, really seems to round everything out.

NP. +26 karma points for having good ears and owning headphones which don't make my and presumably your ears bleed.

Awesome! A rather arbitrary karma number but I'll take whatever, lol.

Btw purrin, when you were trying damping material with these, have you tried the HE400s with the grills off completely and the backs of the drivers open to air? Myself and a couple of others over HF agree that the grills aren't transparent / perforated enough, and that it's causing some slight resonance that reduces the potential soundstage / 3D imaging capabilities of the drivers. Here's a mod I did today, for which I did a writeup, to address this:

http://www.head-fi.org/t/619447/hifiman-he400-he500-re-grilling-mod-56k-dial-up-users-beware

Hey Jerg, did you do that drawing of the lion?

Lol yeah, I'm an avid sketcher. That's just a random 5-min study I did a couple of days ago, scrap paper basically.