Just wanted to post a quick follow up on my DVB #3 build. I took the fiberglass out of the cups which sounded better to me but I was still hearing a very slight distortion. I felt that the treble reflector might actually be vibrating since it is only held in place by 2 thin strips of tape. I removed the treble reflectors and the distortion was gone, midrange is now smooth but i also lost HF extension. Then I decided to try a small square of doubled up transpore tape on the back of the stiff felt, highs may have extended a little but the mids sound nicely refined now. Regardless of fine tuning these headphones are a joy to listen to, I have a hard time taking them off.
Phill