Latency occurs with every digital conversion (AD or DA). Latency is noticeable in audio systems as signal propagation time. In the analog domain the situation is clear: The signal propagation time from input to the output of an analog mixer is always zero. Latencies only existed in the compound midi devices, where external synths or samplers were integrated via midi. In practice, this was not a problem, since the entire monitoring situation always remained analog and thus no latency was audible. With digital mixing consoles or audio interfaces, on the other hand, there is always a delay between input and output. Latency can have different reasons, for example the different signal propagation times of different converter types. Depending on the type and design, a converter needs more or less time to manage the audio signal. For this reason, mixing consoles and recording interfaces always use identical converter types in the same modules (e.g. input channels), so that the modules have the same signal propagation time among each other. As we will see, within a digital mixer or recording setup latency is not a fixed quantity.