A decoder system for providing a stereo signal by complex prediction stereo coding, the decoder system comprising: an upmix stage (406, 407, 408, 409; 1433) adapted to generate the stereo signal based on first frequency-domain representations of a downmix signal and a residual signal, each of the first frequency-domain representations comprising first spectral components representing spectral content of the corresponding signal expressed in a first subspace of a multidimensional space, the decoder system being characterised by the upmix stage comprising: a module for computing a second frequency-domain representation of the downmix signal based on the first frequency-domain representation thereof, the second frequency-domain representation comprising second spectral components representing spectral content of the signal expressed in a second subspace of the multidimensional space that includes a portion of the multidimensional space not included in the first subspace; a weighted summer (406, 407) for computing a side signal by combining the first frequency-domain representation of the residual signal, the first frequency-domain representation of the downmix signal weighted by a real-valued part of a complex prediction coefficient, and the second frequency domain representation of the downmix signal weighted by an imaginary-valued part of the complex prediction coefficient; and a sum-and-difference stage for computing the stereo signal on the basis of the first frequency-domain representation of the downmix signal and the side signal; a first frequency-domain modifier stage (403; 1431) arranged upstream of the upmix stage and operable in an active mode, in which it processes a frequency-domain representation of at least one signal, and a passive mode, in which it acts as a pass-through; and a second frequency-domain modifier stage (410; 1435) arranged downstream of the upmix stage and operable in an active mode, in which it processes a frequency-domain representation of at least one signal, and a passive mode, in which it acts as a pass-through. an upmix stage (406, 407, 408, 409; 1433) adapted to generate the stereo signal based on first frequency-domain representations of a downmix signal and a residual signal, each of the first frequency-domain representations comprising first spectral components representing spectral content of the corresponding signal expressed in a first subspace of a multidimensional space, the decoder system being characterised by the upmix stage comprising: a module for computing a second frequency-domain representation of the downmix signal based on the first frequency-domain representation thereof, the second frequency-domain representation comprising second spectral components representing spectral content of the signal expressed in a second subspace of the multidimensional space that includes a portion of the multidimensional space not included in the first subspace; a weighted summer (406, 407) for computing a side signal by combining the first frequency-domain representation of the residual signal, the first frequency-domain representation of the downmix signal weighted by a real-valued part of a complex prediction coefficient, and the second frequency domain representation of the downmix signal weighted by an imaginary-valued part of the complex prediction coefficient; and a sum-and-difference stage for computing the stereo signal on the basis of the first frequency-domain representation of the downmix signal and the side signal; a module for computing a second frequency-domain representation of the downmix signal based on the first frequency-domain representation thereof, the second frequency-domain representation comprising second spectral components representing spectral content of the signal expressed in a second subspace of the multidimensional space that includes a portion of the multidimensional space not included in the first subspace; a weighted summer (406, 407) for computing a side signal by combining the first frequency-domain representation of the residual signal, the first frequency-domain representation of the downmix signal weighted by a real-valued part of a complex prediction coefficient, and the second frequency domain representation of the downmix signal weighted by an imaginary-valued part of the complex prediction coefficient; and a sum-and-difference stage for computing the stereo signal on the basis of the first frequency-domain representation of the downmix signal and the side signal; a first frequency-domain modifier stage (403; 1431) arranged upstream of the upmix stage and operable in an active mode, in which it processes a frequency-domain representation of at least one signal, and a passive mode, in which it acts as a pass-through; and a second frequency-domain modifier stage (410; 1435) arranged downstream of the upmix stage and operable in an active mode, in which it processes a frequency-domain representation of at least one signal, and a passive mode, in which it acts as a pass-through.