An audio decoder for providing at least four bandwidth-extended channel signals on the basis of an encoded representation provides first and second downmix signals on the basis of a jointly encoded representation of the first and second downmix signals using a multi-channel decoding and provides at least first and second audio channel signals on the basis of the first downmix signal using a multi-channel decoding, and provides at least third and fourth audio channel signals on the basis of the second downmix signal using a multi-channel decoding. It performs a multi-channel bandwidth extension on the basis of the first and third audio channel signals, to obtain first and third bandwidth-extended channel signals, and performs a multi-channel bandwidth extension on the basis of the second and fourth audio channel signals, to obtain second and fourth bandwidth extended channel signals. An audio encoder uses a related concept.