[L-Train]

  I noticed that you're using TXN for the coaxial output?  Why is that?  Won't it be out of phase/inverted?

 
Very keen observation!  One thing to note is that S/PDIF uses biphase mark code, meaning the S/PDIF signal is phase-independent.  Thus, you can actually use either the TXP or TXN pin to drive an optical transmitter or transformer or what have you and it'll work the same.  The main reason I used TXN for the coaxial output is because it made the PCB layout much cleaner.
 
And you're right, I'm using the transformer to invert the inverted signal from the TXN pin.  The reasons for this are rather small/moot: 1) it keeps the D+ and D- pads close together so that you can twist the wires together as closely as possible as "soon" as possible for a tiny, tiny bit better interference rejection (if it didn't invert then the C9 capacitor would have to be placed between the D+ and D- pads), and 2) since we're using a transformer it's essentially "free" and makes the coaxial output the same phase as if you were using the TXP pin (this point was perhaps slightly out of OCD, but like I stated it doesn't matter).

 

[bondsan]

Hello L-Train, thank you for the amazing snes digital audio design.
 
Did you make a eagle schematic and would you be able to post it please
I would like to make a single sided version in Proteus 8.
Plus I don't have the patience ( or funds ) for Osh park and would like the experience
in converting the schematic too improve my electronics knowledge.
 
Thanks.