The 882|20 and ADAT Bridge are designed to soft mute the analog outputs when switching sample rate or sync sources when no valid S/PDIF signal is present, even if set for internal sync.This is to prevent possible full code noise which could be generated if we completely muted/unmuted the DACs (as opposed to simply dimming the DACs) when switching to digital input (which in-turn automatically selects digital sync) with no S/PDIF device connected or turned on.