The invention relates to a method and a device as part of a complete brake system, that is, a brake system comprising a conventional part and a further part, such as a recuperative part, by means of which volume displacements of brake fluid are possible. The method according to the invention and the device according to the invention are used particularly if the pressure conditions in the hydraulic part of the brake system are adapted by the controllable braking force amplifier to a change in the additional braking effect of the further part of the brake system. A blending of the braking effects of the different brake systems into a constant total braking effect is thus accomplished, even if the proportion of the individual brake systems in the total braking effect change. Such a pressure adaptation by the braking force amplifier is generally accompanied by a reaction on the brake pedal, particularly a displacement thereof. The pressure adaptation can take place by means of the volume displacements between at least one hydraulic braking circuit, a compensating chamber, and either an input chamber in the brake pedal or a hydraulic reservoir, without the driver realizing the same at the brake pedal due to a change in position, and thus perceiving the same as disturbing. The method can be used, for example, for vehicles wherein a delay in braking is brought about by operating an electric machine as a generator for generating electricity, and additionally comprising a conventional hydraulic brake system as a further brake system or backup brake system.