The ADAT Bridge is equipped with sample-rate detection circuitry. Essentially, the Bridge I/O can tell if the audio is using a 44.1 kHz or 48 kHz clock. If you are currently set for 44.1 kHz in the software and you send it a 48 kHz clock, either digital or optical, the sample rate will flash indicating the sample rate currently being used is not 44.1 kHz. Likewise, if you are set for ADAT Optical clock and pitch the ADAT more than 1.8% in either direction, the sample rate light will begin to flash.