Best way to dampen a micro-vibrating Printed Circuit Board inside an amp? Thanks!

There are 'off the shelf parts' that are easily purchased, PCB Standoffs come with  Anti Vibration Designs. 

One of the designs discovered will be suitable for the role being selected for it.

A Part on a PCB that has a microphonic property that is audible can benefit, but it is better to treat  the Microphonic issues at the source of the noise, this has been known to remove the audible Microphonics.

Using the PCB anti vibration is not an issue, it would be 'belt and braces' if used in conjunction when treating a Microphonic issue. 

A question for someone to ask, who doubts PCB's pick up Vibration which can be detrimental to the Signal being generated and transferred.

Ask Audio Note why they are having PCB's produced from Panzerholz, which as a a material has the value of the intrinsic properties for Damping/Dissipation well documented.

Ask Taiko why there are components used in their Topology that are Interference Fit into a Panzerholz Periphery Ring. 

I would feel quite comfortable with the notion, both AN and Taiko are making the designs available as a result of Objective Evaluation and not the typical methodology seen on forum, which usually equates to voicing ones "Contempt Prior to Investigation"     

Some of the Best Tube Amp's are Point to Point Soldered, no Circuit Boards and a Schematic that is designed with a Topology for the shortest Signal Path achievable that does not generate noise.

Start adding components to such a Circuit and there is still be the likelihood Microphonics is able to be produced, hence  those in the know and experienced in addressing such matters are quite confident their methods for attaching a part to a chassis, has addressed the issue and is to be a component fitted with an Isolation as part of the mounting.

It is best to take on the idea, it is the Component that has a Microphonic not the Part that enables it to be added to the circuit.