1. A device for generating a complex spectral representation of a discrete-time signal, comprising: a generator for generating a block-wise real-valued spectral representation of the discrete-time signal, the spectral representation comprising temporally successive blocks, each block comprising a set of real spectral coefficients; and a post-processor for post-processing the block-wise real-valued spectral representation to obtain a block-wise complex approximated spectral representation comprising successive blocks, each block comprising a set of complex approximated spectral coefficients, wherein a complex approximated spectral coefficient can be represented by a first partial spectral coefficient and a second partial spectral coefficient, wherein at least one of the first and the second partial spectral coefficients is to be determined by combining at least two temporally and/or frequency-adjacent real spectral coefficients.