Hi Flnntom,
I would suggest that you avoid using materials that ring (granite, Corian, stone, marble, steel, glass, etc) or materials that are resonant (natural wood, Plexiglas, plastic, acrylic, etc) as their inherent characteristics will impart their own sonic signature on the signal that is flowing through the component.
Best,
Barry Kohan
Disclaimer: I am a manufacturer of vibration control products.