This measure is especially effective in the case of tubed electronics. One should only attempt these modifications if they feel comfortable with the task. Another method often reported as effective in tubed gear involved the use of tube damper rings. These compliant rings are placed around smaller signal tubes to damp vibrations in the glass envelope. Several varieties are available, each with its own set of advantages and drawbacks.
Wider designs do a good job of damping due to the large contact area.
The larger contact area however, leads to increased internal envelope temperatures that may significantly shorten tube life. Smaller cross-sectional rings made of rubber avoid the heating problems, but do a poor job of damping. We have adopted a unit featuring a small cross-section, but made from high temperature silicone that exhibits good damping properties. The silicone acts as a bit of a heat sink, actually drawing heat away from the tube. These devices do an excellent job of isolating the tube from structure-borne vibrations.