A method (840, 940) for automatically creating a surround audio mix for playback by a multiple channel audio system, comprising: selecting a subset of a set of rules based, at least in part, on metadata associated with a plurality of stems, each stem being a component or sub-mix of a mix generated by processing one or more tracks, wherein the metadata on the basis of which the subset is selected include a respective voice associated with each of the stems, wherein the voice of a stem is an instrument or group of instruments or sound produced by a musician that contributed to the one or more tracks that were processed to generate the stem, wherein the metadata on the basis of which the subset is selected further include a genre associated with the plurality of stems, the genre being the genre of a song formed by the plurality of stems; and mixing the plurality of stems in accordance with the selected subset of rules to provide three or more output channels for input into the multiple channel audio system, wherein the output channels form the surround audio mix; wherein each rule from the set of rules includes one or more conditions, and one or more actions to be taken if the conditions of the rule are satisfied; the actions included in the selected subset of rules collectively define respective voice positions on a virtual stage for respective voices of each of the plurality of stems; the method further comprising: transforming the voice positions on the virtual stage into mixing parameters for a mixing matrix that, in the mixing step, mixes the plurality of stems in accordance with the selected subset of rules to provide the three or more output channels; and receiving data indicating a listener position with respect to the virtual stage, wherein transforming the voice positions on the virtual stage into mixing parameters is based, in part, on the listener position. selecting a subset of a set of rules based, at least in part, on metadata associated with a plurality of stems, each stem being a component or sub-mix of a mix generated by processing one or more tracks, wherein the metadata on the basis of which the subset is selected include a respective voice associated with each of the stems, wherein the voice of a stem is an instrument or group of instruments or sound produced by a musician that contributed to the one or more tracks that were processed to generate the stem, wherein the metadata on the basis of which the subset is selected further include a genre associated with the plurality of stems, the genre being the genre of a song formed by the plurality of stems; and mixing the plurality of stems in accordance with the selected subset of rules to provide three or more output channels for input into the multiple channel audio system, wherein the output channels form the surround audio mix; wherein each rule from the set of rules includes one or more conditions, and one or more actions to be taken if the conditions of the rule are satisfied; the actions included in the selected subset of rules collectively define respective voice positions on a virtual stage for respective voices of each of the plurality of stems; the method further comprising: transforming the voice positions on the virtual stage into mixing parameters for a mixing matrix that, in the mixing step, mixes the plurality of stems in accordance with the selected subset of rules to provide the three or more output channels; and receiving data indicating a listener position with respect to the virtual stage, wherein transforming the voice positions on the virtual stage into mixing parameters is based, in part, on the listener position. transforming the voice positions on the virtual stage into mixing parameters for a mixing matrix that, in the mixing step, mixes the plurality of stems in accordance with the selected subset of rules to provide the three or more output channels; and receiving data indicating a listener position with respect to the virtual stage, wherein transforming the voice positions on the virtual stage into mixing parameters is based, in part, on the listener position.