Splitting Signal to Multiple DAC’s

If you are using SPDIF with BNC coaxial connectors, you can use a 75 Ohm video coax and use a BNC TEE connector on each input.  This will result in the passive connection, a very common way to do it.  However, this is a 75 Ohm terminated line, so each of those inputs will have a 75 Ohm resistor shunting to ground,  When you get three of them in parallel, you no longer have a perfectly terminated transmission line and you will get reflections up and down the line.  To avoid this, you must use an active SPDIF buffer so that the input is terminated in 75 Ohms and each buffered output becomes a separate 75 Ohm transmission line.  If this was an analog video signal, you could use a one to three video transformer and split it that way, while each line remains at 75 Ohms, there is a resulting loss of power in the three outputs.  One can use this approach with digital signals, too.  Here is an example of one, but uses F-Series connectors. https://smile.amazon.com/dp/B01M34OZ2S/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=f91e24525356a86d19934c46c0666b83&content-id=amzn1.sym.53aae2ac-0129-49a5-9c09-6530a9e11786%3Aamzn1.sym.53aae2ac-0129-49a5-9c09-6530a9e11786&hsa_cr_id=5958461450701&pd_rd_plhdr=t&pd_rd_r=444a4663-e0fe-4006-a7f1-73283e0ccb4b&pd_rd_w=RCQpJ&pd_rd_wg=Ev1Dl&qid=1665513757&ref_=sbx_be_s_sparkle_mcd_asin_0_img&sr=1-1-a094db1c-5033-42c6-82a2-587d01f975e8

If you are using SPDIF with Toslink optical cable, then you must use an active buffer - splitter, as there is no real way to split the optical signal into three and still have good optical signal quality.  Do note that TOSLINK optical cable has a 10 dB loss every meter, so if you need a long connection, then this is probably not a good solution unless the buffer is designed to handle long optical cables.  Likewise, don't increase the optical signal level and then use a short optical cable, as you will most likely overload the input circuitry of the receiving end.  It is wise to read the instructions and follow them!

There is a very good discussion of SPDIF here: 

A good quality SPDIF active splitter with specified jitter should do the job for you. If you are a decent DIY'er,  you can get some useful information here: http://www.hardwarebook.info/S/PDIF_output

 Hope this helps....

Robert

@designsfx 

Hi there, the Sonifex is the transformer splitter I told you about.   The only problem with this approach, if it is a problem, is there is a loss of power in the signal, so you "may" have a loss of fidelity in the digital signal.  Fidelity here means the difference between a "1" and a "0" becomes blurred.  This is where EYE Diagrams and BERT testing will show if this is a problem.  You can Google this to find out what I am talking about if you are interested in that detail.   Clearly, the higher the digital frequency then the more likely this is to occur.  They didn't specify the loss factor in the unit but they did say 100M of coax at 96 KHz, so use that as your guide.  Do make sure your cable is rated 75 Ohms, most video cables are 75 Ohms, so use a good one. 

Note that in a properly terminated 75 Ohm line, the source, the coax cable, and the receiving unit must all be rated at 75 Ohms.  In spite of what is often advertised, RCA jacks can't actually achieve a 75 Ohms impedance, but they can be close.   BNC's are not a problem for 50 or 75 Ohm lines. 

An active device doesn't have the loss factor since it drives each output independently of the others, as each output is buffered.  However, they are more expensive, require power to operate, and overall may not make an improvement in your system over the transformer approach.   So, if you can, experiment and decide for yourself.