An apparatus for generating an output signal having at least two output channels from an input signal having at least two input channels, has an ambient/direct decomposer, an ambient modification unit and a combination unit. The ambient/direct decomposer is adapted to decompose at least two input channels of the input signal such that each one of the at least two input channels is decomposed into a signal of a first signal group and into a signal of a second signal group. The ambient modification unit is adapted to modify a signal of the ambient signal group or a signal derived from a signal of the ambient signal group to obtain a modified signal as a first output channel. The combination unit is adapted to combine a signal of the ambient signal group or a signal derived from a signal of the ambient signal group and a signal of the direct signal group or a signal derived from a signal of the direct signal group as a second output channel.