Ok, so I am assuming that this is a damping mod on a 650, to tone down and clear up low end... Most probably also using damping on baffle as well. I didn't use much damping yet on these type units. Is this referring to the 690 mod? I am assuming that damping was tried to the 650. Ok so I will keep this in mind, as I will deal with the driver control directly, instead of adding materials. I have noted this issue with the HD800 where any damping reduces the air and soundstage. Thats Thats why my next technique on the HD800 does not use damping materials.