Nice test Martin. I've used an assortment of things, from Petra's gel pad (which melted under my DDC), the stock foam pad, and sponges. I then decided to try to cook up something of my own and went to Home Depot for ideas. A rubber trowel for spreading tile grout caught my eye. Five dollars later and a bit of handy work and I had myself a seriously good noise isolation device. Note that I didn't attach it with screws, you don't want the vibrations going through from solid surface to solid surface.