The Retro is a Class II or double insulated electrical appliance. It has been designed in such a way that it does not require a safety connection to electrical earth (ground).
This was done to avoid any chance of earth loops if (for example) Satellite or Cable TV systems are connected.
So it was intended that there is no Earth connection nor is one required.
The presence of high voltages inside the case is inconsequential, as without an earth connection this voltage can only ever offer one pole, even with a short to the case, there is no second pole to complete an electrical circuit.
From a safety viewpoint the Retro is hence safer than Valve Amplifiers WITH an Earth Connection, as in this case a second pole exists.
Testing Procedure:
We use an industry-standard insulation tester to test the Retro according to the required standards for double insulated equipment. This is according to EN 60065 and we also test leakage current according EN 60065 for Class II equipment.
For completeness, we additionally also test according to Medical Equipment directives, even though they are not required to pass.
