Some people are putting an extra foam layer to block the hole on the single foam layer between the earpad mesh and driver. Apperently SOME K701s had 2 layers of foam there, one with a hole and one without. I'm wondering what the one without the hole did to the sound. I'm guessing some of the harshness on some music was controlled down a bit and evened out the soundstage.
It just so happens I have a pair of thin foam layers I would test with tonight so will report back.
Edit*
Typical. The time I need foam inserts and I cannot find a single piece at work whereas normally they are everywhere.