Anybody gone from ethernet to optical for connection to a streamer?

I have both (wired ethernet and fiber).  Fiber is clearly superior.

I have an Etheregen and tried it with both Fiber and CAT and I could not hear the difference. (yes, I had only one hooked up at a time).  The Etheregen switch claims it's "moat" galvanically separates the "in" from the "out". My limited listening test confirmed this in my opinion. That said, I don't know if this helps answer your question, but you might find it useful.  

I’m a little confused are you talking about a fiber connection from your modem/ router to a streamer. If so what type of modem? I’m in the telecom industry but not familiar with any modem that that has fiber outputs only a single input. What equipment is before the streamer?

I can't speak to the optical portion of your question here - but I do know I swapped out my normal, everyday ethernet cable with an "audiophile grade" CAT 7 cable from Pangea. And it introduced the absolute worst ground loop/ hum into my system that I have ever had. (And, I'm still confused about how that happened... I can repeat this, and tried two different cables from them with the same results if anyone is interested.) The optical connection has the potential of reducing ground loop issues, but if you can't hear a hum/ buzz now, it most likely won't make much of a difference. 

Fibre is the best upgrade I have done on my streaming. The OpticalRendu is great. Ethernet direct into a DAC was about the same as my microRendu. Fibre optical was so much better than either of those 2. It was so obvious to me that I immediately bought a second OpticalRendu. I have been using both for about 6 months now on 2 DACs.

The only DAC with Ethernet that I think could be very good and challenge the Fibre optical is the upcoming AudioByte Hub (need the VOX + ZAP).

@jd55 I use this switch for fibre. 
Ubiquiti - UniFi® Switch 8-150W