With tube electronics, I can understand wanting to damp vibration. Tubes are sensitive devices with many precisely aligned delicate parts.

Also I can understand wanting to damp CD players because they involve mechanical motion and sometimes even small jarring can produce read errors.

But when it comes to solid-state electronics -- like an amp or receiver -- I do not understand how typical vibrations can affect the sound. I suppose one way to test this would be to subject a receiver to vibrations far and above what it would ever experience in real-world situations and measure its output for fluctuations.