3M makes some stuff, you can also get car audio padding for that purpose, like Dynamax (get Xtreme).
KP
KP
Component dampening
I have a nice quality tube preamp, but the casework, when tapped or thumped on either the front panel or lid will emit a slight ringing tone. I would like to eliminate this by lining the interior of the front panel and lid with some type of sound deadening substance. Any suggestions on what type(s) of material would help me realize my goal would be appreciated. Thanks...