An apparatus for generating one or more audio output channels is provided. The apparatus includes a parameter processor for calculating mixing information and a downmix processor for generating the one or more audio output channels. The downmix processor is configured to receive an audio transport signal including one or more audio transport channels. One or more audio channel signals are mixed within the audio transport signal, and one or more audio object signals are mixed within the audio transport signal, and wherein the number of the one or more audio transport channels is smaller than the number of the one or more audio channel signals plus the number of the one or more audio object signals. The parameter processor is configured to receive downmix information indicating information on how the one or more audio channel signals and the one or more audio object signals are mixed.