Ok, someone just mentioned the mod for removing the BACK foam behind the driver (not below the pads). What does this change exactly? I read somewhere I believe that it may add in too much bass. I don't want that.
If it adds any extra treble that would be perfectly ok for me.
I found there is a big pro and con with removing the the driver foam. It will open the sound up and will add more "clarity and intimacy" from the mids up. This can seem dramatic on first listen and you may well think wow! But, there is definately more bass and it spills. But the good news is that you can now start experimenting and fine tuning to your taste. Trying different materials in the little driver hole can tighten the bass up. The denser the material the tighter the bass, I shaved a fine piece of foam from an earplug and this really tightens the bass (more so than stock foam). Another one of my favorites was a tiny peice of toiletpaper (tissue). I'm currently using one small layer of thin foam from another headphone and this keeps the open clarity and the bass powerful and tight enough for my preference.
Removing the foam from behind the pads adds a little more clarity too.