So a visit to my parents today and raiding my mom's sewing cabinet yielded some medium density felts and some thin non-breathable packing wrap
I've been fiddling with damping the last couple hours, working on the theme of "reflections are bad" and trying to absorb as much as possible. I figure the big surfaces should be covered with a non-porous material, otherwise sound goes through and reflects off the plastic behind it, which is where the packing wrap comes in. I figure blutak/putty might be better, but I'm trying to keep things light.
On the back of the rings I put a layer of the packing wrap, then a ring of felt, then the same foam/nylon tube as before. On the back of the baffle I put down micropore tape over all the hard surfaces. In front of the driver, one small disk of felt over the main driver opening, a large disk of felt over the entire baffle, then a large disk of foam on top, all squished down beneath the pad. In the rear cup the side is lined with suede, the rear has a ring of felt then a ring of foam.
Treble is now tuned down to manageable levels, bass response is much improved, and I've still got a relatively flat frequency response.
More pics coming later.