1. A loudspeaker-room-microphone system comprising: an input signal path that is configured to provide an input signal; a loudspeaker that is configured to convert an output signal into sound; a recording channel that includes a microphone and that is configured to provide an error signal, the microphone configured to pick up the sound; a filter that is arranged in a signal path downstream the input signal path and upstream of the loudspeaker, the filter configured to filter the input signal according to a controllable transfer function to provide the output signal; and a filter control that is operatively coupled to the filter and configured to control the transfer function of the filter based on the error signal and the input signal; wherein the filter control comprises a combined windowed magnitude and a post-ringing constraint.