Nobody really knows why any particular type of footer will sound good with a particular piece of equipment.
Good point, Psag, although some intuition may just help predict an outcome, e.g., your mention of a rigid, metal coupling of a tube amp would not be my first idea for damping tubes against mechanical vibration. A metal footer may be an effective supplement to a more cushioning layer, but not as a primary connection in all cases. I feel it important to employ at least two approaches to isolate a piece, e.g. sheer mass and soft isolation, or point loading over a big footprint of another material. I am developing a material that will allow for this rule.
Good point, Psag, although some intuition may just help predict an outcome, e.g., your mention of a rigid, metal coupling of a tube amp would not be my first idea for damping tubes against mechanical vibration. A metal footer may be an effective supplement to a more cushioning layer, but not as a primary connection in all cases. I feel it important to employ at least two approaches to isolate a piece, e.g. sheer mass and soft isolation, or point loading over a big footprint of another material. I am developing a material that will allow for this rule.