A method in a decoder (100, 300, 600) for decoding a plurality of audio signals for playback on a speaker configuration with N channels, the plurality of input audio signals representing encoded multichannel audio content corresponding to at least N channels, the method comprising: receiving M input audio signals, wherein 1<M≤N≤2M; decoding, in a first decoding module, the M input audio signals into M mid-signals which are suitable for playback on a speaker configuration with M channels; for each of the N channels in excess of M channels: receiving, by a stereo decoding module, one of the M mid-signals (126, 326, 626); receiving, by the stereo decoding module, a side signal (124, 324, 624) corresponding to the mid-signal; and decoding, in a stereo decoding module, the side signal and its corresponding mid-signal so as to generate a stereo signal (128, 328, 628) including a first stereo signal and a second stereo audio signal which are suitable for playback on two channels of the speaker configuration, wherein the received side signal is a first waveform-coded signal comprising spectral data corresponding to frequencies up to a first frequency (k 1), and the corresponding mid-signal is a second waveform-coded signal comprising spectral data corresponding to frequencies up to a frequency which is larger than the first frequency, and wherein the decoding of the side audio signal and its corresponding mid-signal comprises upmixing the mid-signal and the side-signal so as to generate the stereo signal, wherein for frequencies below the first frequency the upmixing comprises performing an inverse sum-difference transformation of the side signal and the mid signal, and for frequencies above the first frequency the upmixing comprises performing parametric upmixing of the mid signal, whereby N audio signals which are suitable for playback on the N channels of the speaker configuration are generated. receiving M input audio signals, wherein 1<M≤N≤2M; decoding, in a first decoding module, the M input audio signals into M mid-signals which are suitable for playback on a speaker configuration with M channels; for each of the N channels in excess of M channels: receiving, by a stereo decoding module, one of the M mid-signals (126, 326, 626); receiving, by the stereo decoding module, a side signal (124, 324, 624) corresponding to the mid-signal; and decoding, in a stereo decoding module, the side signal and its corresponding mid-signal so as to generate a stereo signal (128, 328, 628) including a first stereo signal and a second stereo audio signal which are suitable for playback on two channels of the speaker configuration, wherein the received side signal is a first waveform-coded signal comprising spectral data corresponding to frequencies up to a first frequency (k 1), and the corresponding mid-signal is a second waveform-coded signal comprising spectral data corresponding to frequencies up to a frequency which is larger than the first frequency, and wherein the decoding of the side audio signal and its corresponding mid-signal comprises upmixing the mid-signal and the side-signal so as to generate the stereo signal, wherein for frequencies below the first frequency the upmixing comprises performing an inverse sum-difference transformation of the side signal and the mid signal, and for frequencies above the first frequency the upmixing comprises performing parametric upmixing of the mid signal, whereby N audio signals which are suitable for playback on the N channels of the speaker configuration are generated. receiving, by a stereo decoding module, one of the M mid-signals (126, 326, 626); receiving, by the stereo decoding module, a side signal (124, 324, 624) corresponding to the mid-signal; and decoding, in a stereo decoding module, the side signal and its corresponding mid-signal so as to generate a stereo signal (128, 328, 628) including a first stereo signal and a second stereo audio signal which are suitable for playback on two channels of the speaker configuration, wherein the received side signal is a first waveform-coded signal comprising spectral data corresponding to frequencies up to a first frequency (k 1), and the corresponding mid-signal is a second waveform-coded signal comprising spectral data corresponding to frequencies up to a frequency which is larger than the first frequency, and wherein the decoding of the side audio signal and its corresponding mid-signal comprises upmixing the mid-signal and the side-signal so as to generate the stereo signal, wherein for frequencies below the first frequency the upmixing comprises performing an inverse sum-difference transformation of the side signal and the mid signal, and for frequencies above the first frequency the upmixing comprises performing parametric upmixing of the mid signal,