In audio processing technology there are interfaces of different type, the different interface types being associated with differing sample clock frequencies and/or differing data frame or data word formats. In some applications it is desired do process audio signals that stem from such interfaces of different type. According to the invention the input signals of the interfaces of different type are pre-processed for a subsequent common-format central processing, using a synchronization to the common system clock, channel decoding according to the differing channel protocols related to the different-type interfaces, and processing the resulting PCM bitstream format signals so as to form therefrom sample words that are stored in an intermediate store from which the sample words are fed to the central processing.