Dekoni Audio Fostex TH900 Elite Hybrid arrived today.
So
@koover was right. The change is incredible easy.
What wasn‘t easy: being honest that the Dekoni pads changed the headphones to the worse.
It is important to mention that I only wanted to swap the pads as my ears start to hurt in the originial TH-X00 Ebony pad. Also I love to listen to music while lying in bed and the form of the original pads does not allow this.
When I had put on the Dekoni pads I felt like a lot of the front oriented 3D sound was gone and also the bass had changed. So I inspected the original pads. closer.
As one can see clearly only a part of the sound of the speaker is allowed to get directly to ear. The rest is bouncing back building up some reflections.
Plus, the „opening“ is not in the center but closer to the front, so further away from the thicker pad part.