Where should I go from here with my digital front end?

Another vote for decoupling the noise from the copper lan cables with fiber right before the streamer.  I use an ifi silent power ps for the fiber back to copper conversion box with audioquest rj45 1ft cable to streamer. All for less than $300. I believe galvanic isolation is the only thing that matters with the digital network assuming you have a solid gigabit network...

Thanks everyone for responding.

I've decided to try the fiber converter route with power supply from Amazon totaling  $163 all in. No brainer in not giving it a shot especially with amazon's easy return policy.

Should have it by Wednesday. I'll report back

Here’s the thing with the fibre optic conversion…it’s resilient to the EMI and RFI after the signal is converted into fibre optic, however the converter modules themselves introduce their own garbage into the signal. In my system it manifested itself as glare, glassy and thin sound and that didn’t work out for me. YMMV.
 

You have to find the solution that does the least amount of harm while removing what doesn’t belong in the signal.
That is why ultimately I returned the fibre optic converters and went for the passive Network Acoustics Eno streaming system.

I agree with Amazon return policy it would be a sin not to try this fibre optic stuff. If it works for you, that’s an awesome first step. 

Be sure to try LPS with at least last FMC before passing judgment, lps on both even better. The lps insures the garbage emanating from the FMC will be eliminated, switch mode power supplies injecting the noise.

I also mentioned the Sonore optical products as upgrade to the generic FMC. Better clocks and internal power supplies within these products substantial improvement over generic. Still need quality LPS with this. In the case feeding streamer one would use two Sonore OpticalModule in series.

Optimized optical is pretty hard to beat, even the generic with lps very nice.

OP,

I look forward to hearing your evaluation.