I would be remiss if I didn’t mention that mechanical stress and strain are not good for the sound. Without getting too far afield you can test this theory by using ordinary plastic spring loaded clothes hangers, attaching them to interconnects and hearing how it hurts the sound. One of the benefits of Cryogenically treating audio related things, e.g., CDs, LPs, cables, tonearms, even musical instruments such as trumpets, flutes, etc. is the reduction of mechanical stress and strain 🥵 Coincidence? You decide. So, you could say there’s a fine line between adjusting pressure on audio things like speakers and components, trying to reduce vibration, and producing mechanical stress and strain that hurts the sound - either directly or indirectly.
If tapping on a component or shelf hurts the sound don’t tap on them while the music is playing. So I disagree that tapping gives you much of a clue about what’s going on. For example, the ringing or clunking sound produced by tapping a large thick slab of granite with a small hammer 🔨 cannot be reproduced by acoustic waves or seismic vibrations in the room. They aren’t energetic enough. Thick granite slabs are not very vibratory. Obviously, it depends on the material, mass (inertia) and size especially thickness.
If tapping on a component or shelf hurts the sound don’t tap on them while the music is playing. So I disagree that tapping gives you much of a clue about what’s going on. For example, the ringing or clunking sound produced by tapping a large thick slab of granite with a small hammer 🔨 cannot be reproduced by acoustic waves or seismic vibrations in the room. They aren’t energetic enough. Thick granite slabs are not very vibratory. Obviously, it depends on the material, mass (inertia) and size especially thickness.