[betweenpie]

I've dug around a bit but haven't found anything in the many Denon pages here similar to this, so I'll start a thread. Please let me know if one already exists.
 
I've been toying around replacing the foam rings that sit between the earpad piece and the driver proper. The rings are easily accessed and removed. Much of the bass and imaging in these phones is controlled by these rings - take them out and give a listen...all the bass goes away.
 
I think the Denons are well designed, and I'm all for mass-produced industrial manufacturing, but it seems to me we could do better than that piece of foam.
 
I've created replacements out of 1/4 " industrial felt. The result so far are pretty promising. Picture below. Note that I mimicked the four cutouts on the outer edge, as I believe these affect the overall sound a bit. I added a coating of wood glue to the inner ring, to tighten things up a bit. It worked.
 
The main improvement is in imaging (which wasn't bad to begin with, but tweak we must). Bass is decreased a very tiny bit, midrange boosted minimally. It is mostly a different flavor, not better or worse. The felt can be great on certain recordings, no improvement on others. I haven't yet heard anything the felt sounds bad with but that logically should happen at some point.
 
If wanted I'll post further developments...