The electrodynamics of a loudspeaker is affected by several nonlinear phenomena, mainly due to mechanical suspensions, coil with ferromagnetic core and temperature variations. In this paper we address the numerical correction of distortions in the high level response of these systems. The proposed method is based on one hand on the port-Hamiltonian approach for passive system modeling (including the nonlinear case), on the other hand on the flatness approach for exact trajectory planning (here the displacement of the loudspeaker's diaphragm). The model includes a simple linear acoustical load and a phenomenological position saturating nonlinear spring effect due to the suspension. The feed-forward controller is built and simulation results are shown. The method is applied here on a simulated system, with the perspective to be applied on a real device.