I use FMC (ethernet-fiber-ethernet) from ER port B to the streamer and it improves sound.
I tried using the ER SFP input, but it degraded sound in comparison to ER ethernet input in port A.
Here is an issue that puzzled me. I upgraded all SFPs to the Finisar 1324, but the ER wouldn't work with it. The ER works well with the cheapo SFP I bought from Amazon.
I think the ER prefers the ethernet input. I will next try the FMC (ethernet-fiber-ethernet) method between the ethernet source and the ER.