Consistent with an example embodiment, there is a signal processing circuit. Linking multiplexing (L-MUX) circuits, link respective pairs of stream processing circuits. Each L-MUX circuit is individually switchable to a normal mode and a replacement mode; in normal mode, it passes a first stream of samples values between the stream processing circuits in the respective pair of the L-MUX circuits; in replacement mode, it supplies successive sample values from a second stream from the communication structure to a receiving one of the stream processing circuits in the respective pair. A control circuit keeps a selectable one of the multiplexing circuits in the replacement mode so the selectable one of the L-MUX circuits passes a stream of successive samples from the second stream to the receiving one of the processing circuits in the respective pair of L-MUX circuits, while keeping at least part of the other L-MUX circuits in the normal mode.