According to the [URL="http://www2.clipsal.com/cis/__data/page/4172/MRA_Audio_Amplifier_Users_Guide_F1913-02.pdf"]manual here[/URL] on page 7, the analog input is sent to the digital output so that the amps can be daisy-chained when in stand-alone mode (which is my situation). If the MRA digital input is sent to the digital output for daisy chained operation and the analog is also sent to the output it is logical to believe that the optical input is also treated the same way. That is all assuming that the manual is correct as well. I dont have a MRA - I am just using stand alone mode so not being able to use the MRA digital input is not an issue. My test I referred to in the previous post was an analog input with the digital out connected to the digital in of a daisy chained amp. I was not able to get audio out of the second amp but that may have been because I could not confirm that I had selected the digital input.