niodari, my experience is that Toslink is poorer as a link in comparison to digital coax. There may be exceptions, but I have not encountered any yet. The discussion on upgrade here is conversion from ethernet to optical. I would not make the mistake of thinking that because the Toslink is inferior to your DAC, it would not be efficacious to use optical connection in eliminating noise/improving the playback by replacing Ethernet. I wrote the article the OP is referencing in regard to the SMC/SONORE products, and discourage people from the conclusion that these two implementations of fiber optic result in similar outcomes.
I also encourage people to listen to those who have done demo, owned and/or compared.
I also encourage people to listen to those who have done demo, owned and/or compared.