Bleargh. The fenestrated sheepskin pads are frustrating. Overall, they work best on the HD600 for me. I did have a pretty sublime experience with them and the HD650 listening to Kinda Blue at a lower volume than I might normally. Then the new Bjork album, Utopia was totally unlistenable...but with the regular pads it was flawless. More consistent on the 600... I guess it's like having a 'Loudness' switch on the headphone. I would say that there is an increase in image stability, maybe due to the denser material. I wonder if the sound will change as they change shape...or how much my ear will adapt.