Ok, thank you for explaining
So there seems to be a difference, just not in the bass and according to Rin it's not a "substantial difference".
This could be true. I'm not experiencing a substantial change with the mod, even though there is an audible change, it still sounds like a k701. But it does not sound like a change in the highs. But if you take some of the highs away the lows will come forward... I guess.
I am still a bit confused though as Rin is only talking about "blocking" vents and not about "opening" vents, which seems to imply that "stock" is with the vents open, and thats not at all like my k701.
Are you completely sure that Rin is not only talking about blocking the rear grille and all the other holes around the back of the cup?
That would actually make more sense given the measurements. It's like covering the rear of the cups with your hands, which does make the highs more mute, so to speak.