Audio processor for processing an audio signal, the audio signal comprising metadata, the audio processor comprising: an audio signal modifier configured to modify the audio signal in response to a user input to obtain a modified signal; a loudness controller configured to determine a loudness compensation gain based on the one hand on a reference loudness or a reference gain corresponding to an original audio scene and on the other hand on a modified loudness or a modified gain, wherein the modified loudness or the modified gain depends on the user input, wherein the audio processor is configured to compute a loudness normalization gain based on transmitted loudness information included in the metadata and a target loudness level set by the user input, and a loudness manipulator, wherein the loudness manipulator is configured to manipulate a loudness of the modified signal using the loudness compensation gain, wherein the loudness manipulator is configured to apply the loudness compensation gain together with the loudness normalization gain to the modified signal, and wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal indicating which group is to be used or is not to be used for determining the loudness compensation gain, and wherein the group comprises one or more audio elements, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal referring to at least one preset, wherein the preset refers to a set of at least one group comprising one or more audio elements, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal indicating whether a group is switched off or switched on, wherein the group comprises one or more audio elements, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal with at least one group loudness missing in the metadata of a group comprising one or more audio elements comprised by the audio signal, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal referring to a playback configuration for a reproduction of the audio signal. an audio signal modifier configured to modify the audio signal in response to a user input to obtain a modified signal; a loudness controller configured to determine a loudness compensation gain based on the one hand on a reference loudness or a reference gain corresponding to an original audio scene and on the other hand on a modified loudness or a modified gain, wherein the modified loudness or the modified gain depends on the user input, wherein the audio processor is configured to compute a loudness normalization gain based on transmitted loudness information included in the metadata and a target loudness level set by the user input, and a loudness manipulator, wherein the loudness manipulator is configured to manipulate a loudness of the modified signal using the loudness compensation gain, wherein the loudness manipulator is configured to apply the loudness compensation gain together with the loudness normalization gain to the modified signal, and wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal indicating which group is to be used or is not to be used for determining the loudness compensation gain, and wherein the group comprises one or more audio elements, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal referring to at least one preset, wherein the preset refers to a set of at least one group comprising one or more audio elements, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal indicating whether a group is switched off or switched on, wherein the group comprises one or more audio elements, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal with at least one group loudness missing in the metadata of a group comprising one or more audio elements comprised by the audio signal, or wherein the loudness controller is configured to determine the loudness compensation gain based on the metadata of the audio signal referring to a playback configuration for a reproduction of the audio signal.