I have had a few requests by PM to re-summarize my latest configuration. This is virtually identical for the 5000 pads or the stock pads, with one exception, which I'll detail later.
Inside:
1) Using plasticine (modeling clay) to damp the front baffle.
2) Entire back of cup covered in paxmate (not the outer perimeter, there's no audio bouncing around in there, or shouldn't be...
3) Removed the white cover over the driver and replaced with a stiff felt, glued with a 360 degree bead of rubber cement
4) Felt removed from the vent, and the vent ~90-95% covered with electrical tape (interestingly the stock pads and 5000 pads tuned almost identically). This is a very crucial adjustment. When the vent is stock, or more so wide open, bass is totally boomy, peaky and under damped. Individual preferences will vary, as will the tuning based on which pads one uses, which felt, etc. The best way to tune it is to start with it 100% open then "dial in" a rough estimate of the coverage needed over the vent. To do this I simply "sealed" it by pressing gently with my fingers from the outside, and gradually rolling them to open a little of the vent. It's pretty dramatic, you'll hear the bass adjust in level and damping, as well as the soundstage and midrange.
Outside:
1) Cut the felt away from around the driver. With the 5000 pads, I left the driver exposed, and lifted the back of the pads about 1/8" using a piece of weatherstipping. The stock pads, on the other hand, had a sibilance to them that a thin layer of soft felt over the driver fixed.
2) Surround the driver on the baffle with Paxmate.