We have been working hard to eliminate mains transformer buzz generated in the windings and isolation material.
But the core hum/vibration, caused by so called magnetostriction is not possible to totally eliminate in iron cores.
A way to reduce the mechanical coupling between the transformer and any resonating chassis is to use vibration isolators.
Therefore, for your convenience, we now offer rubber vibration isolators suitable for our mains transformers with M4 mounting holes.
Datasheet