The best aftermarket pads are the Dekoni Elite Velour but they will change the sound of the headphone. Pads play a very big role in the tuning of a headphone.

As far as the headband goes, some people like to put the Dekoni nuggets and they say it improves comfort.

As far as the clamp force goes, the headband is made out of metal and you can bend it to your liking to reduce the clamp. I suggest you try this first before you start investing in pads.