Well, to drill the holes, I started by figuring out where the rough center was on the cups. So, on the inside of the cups, I drew straight lines connecting the four screw pegs, which crossed each other at the center point of the cups. From there, I drilled a small hole. To do this, you need to find a way to keep the cups stationary while still having space below so that you can drill through them.
Next, I used a drill bit piece similar to this. The differences is that the serrated circular part made a full circle, and the serrations themselves were smaller and less pronounced (there were more teeth on the bit). It also wasn't 3", haha. I don't know the exact size I used, and I'm not even sure if it was technically a forstner bit. For this, I laid the cups on a wooden work bench (something that is meant to get beat up) with the logo facing up. I then held the cups in place while I slowly bored out a hole in the cups with that drill bit. Yes, I used my hands to hold them in place...probably not the best idea, but I still have my hands!
Edit: I guess the drill bit piece is technically called a hole saw of sorts.
After that, I used a high grit sand paper to smooth off rough parts that were left over, taking care to not scratch the cups themselves in a visible way (which I did anyway...oops).
That's it! I only had access to the tools because I was staying with my parents before school started back up. I'm no expert at all with tools, so I'd imagine most people would be able to do this assuming they have the tools needed.
Can I ask, lee730, if you also have the earpads resting on the frame of the headphones while you have the cups off? I can't tell by your post. I personally did not like the sound of them being open if the earpads were locked in like normal. It sounded way too muddy and slow, IMO.
I think it would be interesting to see if there are any earpads that could be used in place of the stock ones that could still be locked in place and yet not muddy up the sound.
Edited by hans030390 - 9/19/11 at 11:12pm