You may already be aware of this, but there is varnish over that copper. To use grounding effectively, you either have to find a spot that is unvarnished or scratch a tiny bit off where the grounding post (or similar) will reside.Kondo does not employ aluminum but copper for their chassis. Copper is an ideal material for grounding and this provides the possibility to lower the noise floor very significantly, provided you use top notch grounding.