Audio encoder and method for scalable multi-channel audio coding, and an audio decoder and method for decoding said scalable multi-channel audio coding

An audio encoder for encoding a multi-channel audio signal includes an encoder combination module (ECM) for generating a dominant signal part (m) and a residual signal part (s) being a combined representation of first and second audio signals (x1, x2), the dominant and residual signal parts (m, s) being obtained by applying a mathematical procedure to the first and second audio signals (x1, x2), wherein the mathematical procedure involves a first spatial parameter (SP1) including a description of spatial properties of the first and second audio signals (x1, x2), a parameter generator (PG) for generating a first parameter (PS1) set including a second spatial parameter (SP2), and a second parameter (PS2) set including a third spatial parameter (SP3), and an output generator for generating an encoded output signal having a first output part (OP1) including the dominant signal part (m) and the first parameter set (PS1), and a second output part (OP2) including the residual signal part (s) and the second parameter set (PS2).