@agillis, to enjoy the benefits of fiber optic isolation, it looks like you need both an opticalModule and fiber ethernet converter. But in some of the other threads I've read about your product (Roon community), people suggest using two opticalModules. Can you explain which configuration is correct and why anyone would need two opticalModules? Thanks.
In my testing here using an opticalModule on both ends didn't make much of a difference. Using on the "clean" end of the fiber gave a noticeable improvement in sound.
But the Roon community members are not the only ones who heard a difference with an opticalModule on the "dirty" end. Hans Beekhuyzen a youtube reviewer also says his opticalRendu sounds best with an opticalModule on the "dirty" end. You can watch his video here.
https://www.youtube.com/watch?v=q0A0l6keKTg
I have noticed that any time you eliminate switching power supplies from the area around your audio system the sound can improve. That may be what is happening here.