A decoder system for providing a stereo signal by complex prediction stereo coding, the decoder system comprising: an upmix stage (206, 207, 210, 211; 306, 307, 308, 309, 312; 406, 407, 408, 409; 1410; 1421; 1433) adapted to generate the stereo signal based on first frequency-domain representations of a downmix signal (M) and a residual signal (D), 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 upmix stage comprising: a module (206; 306, 307; 408) 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, wherein the module is adapted to determine the second spectral components of the downmix signal by applying a Finite Impulse Response, FIR, filter to combine at least two of the first spectral components of the downmix signal; a weighted summer (210, 211; 308, 309; 406, 407) for computing a side signal (S) on the basis of the first and second frequency-domain representations of the downmix signal, the first frequency-domain representation of the residual signal and a complex prediction coefficient (α) encoded in a bit stream signal; and a sum-and-difference stage (207; 312; 409) for computing the stereo signal on the basis of the first frequency-domain representation of the downmix signal and the side signal, wherein the upmix stage is further operable in a pass-through mode, in which said downmix and residual signals are supplied to the sum-and-difference stage directly. a module (206; 306, 307; 408) 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, wherein the module is adapted to determine the second spectral components of the downmix signal by applying a Finite Impulse Response, FIR, filter to combine at least two of the first spectral components of the downmix signal; a weighted summer (210, 211; 308, 309; 406, 407) for computing a side signal (S) on the basis of the first and second frequency-domain representations of the downmix signal, the first frequency-domain representation of the residual signal and a complex prediction coefficient (α) encoded in a bit stream signal; and a sum-and-difference stage (207; 312; 409) for computing the stereo signal on the basis of the first frequency-domain representation of the downmix signal and the side signal, wherein the upmix stage is further operable in a pass-through mode, in which said downmix and residual signals are supplied to the sum-and-difference stage directly. <EOS>