Impedance is very important in digital transfers and must be closely matched. AES = 110 ohms, standard XLR cable, S/PDIF = 75 ohm, RCA connector. Using a Y-cord to split a digital signal to multiple devices is not advised for reliable transmission.AES/EBUAudio Engineering Society/European Broadcast Union - A balanced configuration that connects pin 1 to the signal ground, while pins 2 and 3 are used to carry signal data. Low impedance in nature (110) with waveform amplitudes that range between 3 and 10 volts. Maximum cable length of up to 328 feet (100 meters) without encountering undue signal degradation.Digital audio channel data and sub-code information is transmitted in blocks of 192 bits that are organized into 24, 8 bit words. Within the confines of these data blocks, two sub-frames are are transmitted during each sample period that convey information and digital synchronization codes for both channels in a L-R-L-R... fashion.Because the data is transmitted as a self-clocking Bi-Phase code, wire polarity can be ignored, and the receiving device will receive its reference clock timing from the digital source device.S/PDIFSony Phillips Digital Interface - Used for transmitting digital audio between consumer digital audio devices; it is similar in data structure to its professional counterpart AES/EBU.Instead of using a balanced 3-pin XLR cable, the S/PDIF standard is an unbalanced phono (RCA) connector, which conducts nominal peak-to-peak voltage levels of 0.5 volts with an impedance of 75 ohms. In addition, transmissions via optical lines that use the TOS link connection cable generally use S/PDIF data protocol.S/PDIF channel data and sub-code information is transmitted in blocks of 192 bits; however, they are organized into twelve 16 bit words. A potion of this information is reserved as a category code that provides the necessary setup information (sample rate, copy protection status, and so on) to the copy device. A portion of the 24 bits set aside for transmitting audio data is used to relay track indexing information, such as start ID and program ID numbers, enabling this relevant information to be transferred from the master to the copy. It should be noted that the professional AES/EBU protocol isn't capable of digitally transmitting these codes during transfer.***Information collected from Modern Recording Techniques 4th ed. by Huber & Runstein.