Perhaps it's a difference in foam cell. Purrin and myself definitely hear them as the graph shows. Though, it just occurred to me that we don't have a reference for any of the older HD800s using this mod w/ the supposed 6k nastiness. Are you an early or late model HD800? Just curious.
Anyway, if you get the best sound as is, hell that makes things easier. Though experimenting with different materials is a possibility to consider since the phones are the only things we are likely to have in common. Purrin and myself tuned off the same setup.
Thanks for your input Anax. You've brought up some points to consider. I don't hear it as the graph shows, which means there must be a difference in the foam I'm using. It looks the same, but it doesn't mean it's identical.
Also, aside from the frequency response, I'm definitely hearing a reduction in air/openness and soundstage. The more I obstruct the open mesh grill, the more pronounced the effect.
My HD800s are a late model, #9311. I've found the silver cable has already removed the hash/grain in the treble while increasing speed and microdetail. I guess I don't need the mod, but I'll try out some other materials out of curiosity.