Better sound at night?

[BoyScout]

Where or how do they ground the box? Isn't it floating ? Do they clean the D.C. noise or actual grounding it ?

The whole is called foundation grounding. When building the house, a grounding line is laid in the concrete floor of the house. At one end the earthing strip is led out of the concrete and serves as a connection for the potential equalization (see picture, gray box on the wall). Afterwards, the grounding tape can also be laid in the earth.

My house must have something like that somewhere (under the house?), because we have ground (hearth) in all the electical outlets.
What i´m asking for is, if possible, how to do a simple grounding set just for the equipment.
There must be a way to do it, right?