Scalable multi-channel audio coding

An audio encoder adapted to encode a multi-channel audio signal. The encoder comprises an encoder combination module (ECM) for generating a dominant signal part and a residual signal part being a combined representation of first and second audio signals, the dominant and residual signal parts being obtained by applying a mathematical procedure to the first and second audio signals. The mathematical procedure involves a spatial parameter comprising a description of spatial properties of the first and second audio signals. Embodiments include a plurality of interconnected encoder combination module, so that e.g. six independent 5.1 format audio signals can be encoded to a single or two dominant signal parts and a number of parameter sets and residual signal parts.