I'll likely pick up the Ether pads eventually. About the dynamat, are you saying you apply it to the metal bars across the driver? If you don't mind, a bit more detail on exactly what you have done with it would be great!
I use felt on the main bar in the center facing inside. the dynamat would foul the cloth, and maybe get on the membrane! Don't do it.
1. fuzzor - many fine descriptions of this step
2. back screen off, I use 1/2" ground cloth (which is metal not cloth); make sure you cut it accurately, and work it so you have a single piece of metal going into each of the retaining holes so they fit well, and make sure you sand them down, and clean them up to avoid any sharps issues (your hands or the membranes) - I spray painted mine black for looks.
3. before you do the final fit of the screens, add the dynamat to the back of the can, along the edge where the membrane mounting plate fits the the headphone body. No need to overdo it or leave any extra in a spot that might touch the membrane.
4. get a copper cable to replace the rancid SPC stock stuff. Hit the jackpot with an old Black Dragon v1, but I'm sure many would be as/nearly as good.
5. install the Ether angled pads - line them up so that the stators look even through the dust fabric, not important per se - but means your pads are lined up vs each other.
6. when not in use store them in a gallon plastic bag or the box - since the rear screen dust protector is gone.
7. Not sure that putting felt on the bar does anything but, there might be a placebo benefit - or more.
8. They like watts, not as greedy as the HE-6, but 2 min, 4 better. They like transistors with quick hard bass (Rag 1 suits them).
9. Oops, forgot: I use the 4XX headband instead of degrading stock one - now on my 4xx.
10. the above mods have lost me some bass under 60 hz. I'm going to work on getting the pads more sealed down to cut leakage and see if that helps.
Honestly modded up this way, they are easier to take then unmodded HE-6, and often sound better, although for mid/high detail and low end eye closing bass the 500 can't compete. But somehow my 500 sounds more coherent. Wish I had fully modded set of HE-6's to find out more.
Tonight they are beating the HEX v2's on everything.