Hey guys, good news bad news but first I want to acknowledge
@atomicbob and his experiment, I read what you did and have some questions. I may want to try replicating your ASIO bridge setup to try it myself with a Breeze Du-u8 and the R3 for a simultaneous control over two output devices. I want to say that while the U12 is a fantastic device I believe that the R3 is a step up so I want to see where things may have changed.. read: does the ASIO bridge/virtual soundcard setup make sq difference void because of how it processes the audio and possibly added (for the lack of words) goobleygook to the audio signal?
So the good news bad news, from my phone call to Focusrite and having a chat with their Rednet specialist: The good news is the Rednet 3 is capable of outputting to multiple DACs and I've confirmed this to be possible but only via AES/EBU breakout cable (Tascam format not Yamaha).
The output signal on the optical is not your standard spdif optical but adat optical widely used in pro sound. Unfortunately our DACs are incompatible with only 2ch optical spdif. ADAT is capable of carrying multiple channel signals over optical where as spdif is your standard 2ch; in short the Rednet 3 can't output to our DACs via optical without some kind of conversion from ADAT to SPDIF -- which I'm not sure exists. I'm sure it does but having it in the chain will probably defeat the purpose.
So unless you're using a DAC that takes ADAT via optical input, the R3 can not send a signal to your DAC.