My Audeze pads arrived today! I took the ring out of them and stretched the sleeve around the outer shell on each side. I'm going to put the double-sided sticky tape on the HE-6 inner ring like what ohgourami did and press the pad into it. Very initial impression is that the sound is more "out of your head" now, with a slight drop in treble and a slight increase in sub-bass over the stock velours. I like it! Now I can't wait for my sticky felt to get here so i can install that, along with a new headphone cable :)
I actually kept the stock ring that came with the pads! I figure it shouldn't make much of a difference but I wanted the extra rigidity for the pads.
Do the felt mod and make sure you take out the cotton from the rear grill. Taking out that cotton and foam is essential for the HE-6 to sound good with the felt mod!