Last evening, when assembling my pair again ... for the 12th time, I did realize I had some reflex dot possibilities. However, I also had the 1/8" thick sheets of closed cell craft foam with an adhesive backing. I covered 2 of the 9 squares on the back of the drivers. This, for me, did the right thing for the treble to lift the sound enough to my liking.
I haven't used the "teased" cotton balls yet. I did try the pads of cotton the first time around. I'm not sure of hearing the difference between them, or not. I should try the balls this time around, though. Also, I haven't closed any of the bass vents off, yet. I'm kind of keeping those open for fear that I'd be building the T40RP, which has the same drivers and the vents are closed off. However, the criticism with the T40RP seems to be with the cup size. Being of a smaller volume area, the sound is weakened and it's a harder headphone to modify.