Methods and systems for modulating an input electrical signal are disclosed and may comprise modulating input signals utilizing a digital Class-D modulator and generating a digital output signal that is proportional to the input signals. The apparatus also includes structure that directs a flow of the fluid coolant in the form of a liquid at a subambient pressure in a manner causing the liquid coolant to be brought into thermal communication with the heat-generating structure. This is known as \u201cequal force presence. When the insulated body is seated on the support seat of the fixing member, the contact sections of the terminals pass through the terminal holes in the insulated body and are retained within the plug reception chamber.