Can I connect AES/EBU to S/PDIF ?
Yes, in most cases. Please refer to the text below:
On most consumer equipment, S/PDIF or IEC 958 is used instead of AES/EBU.
With some limitations, this type of signal can often be interfaced to AES/EBU, if you follow the guidelines given below.
Some S/PDIF equipment may reject a signal because the Status Bits are set according to the AES/EBU specification, but in most cases (non-consumer equipment) professional status bits are accepted, and a signal may be transferred.
AES/EBU output to S/PDIF input
To get the most reliable interface, the noise immunity of the electrical interface should be maximized.
Drive level and impedance is higher with the AES/EBU interface, so the best solution is to use a resistor network as shown below to match both parameters.
On some equipment, an S/PDIF input processes 16 bits, on other 20 or 24 bits. You should find out how many databits is being processed, and set the AES/EBU output dither accordingly. - All TC Electronic units process all 24 bits.
Most consumer units with S/PDIF inputs may reject AES/EBU status bits.
AES/EBU output to S/PDIF input Cable - with impedance and level matching
S/PDIF output to AES/EBU input.
Unless your S/PDIF transmitter uses the 4 aux data bits for something else than audio (which is very unusual today), the problem from going S/PDIF to AES/EBU is typically electrical.
The best solution is to use an active balanced digital line driver close to the S/PDIF output, and 110 ohm cable onwards, but for short term setups, you may get by more easily: A 75 ohm cable with a RCA phono type of connector in one end directly into a XLR male plug wired like shown on the drawing below..
Because of the low level and unbalanced output signal, the cable should be kept short (less than around 5 meter).
S/PDIF output to AES/EBU input cable, Neither with impedance nor level matching