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

It's easy. I stream through Lumin. It's great. I have 1000s of CDs I play through a high end Vd player. But if you want better sound, it's easy. Go vinyl. It will always be more pleasurable to your ears. It just will. My vinyl playback cost less than my streamer and CD player but is my go to first choice. 

I feel from where you are presently, a good Ethernet re-ganerator would be a logical step. I had good digital Ethernet and USB cables however when I added the EtherREGEN by Uptone-Audio, that made the most difference in cleaning up the noise and improving the micro-detail than any cabling changes I made. Uptone-Audio will soon be releasing their 2nd-Gen EtherREGEN device which I will be purchasing and either selling mine or giving it to my best friend.

Good Luck in your digital improvement decisions and search.

Hi @emil, I agree with @audphile1 here and have also avoided Fiber for those reasons.  Plenty report it either is or is not an improvement.  I recommend the Acoustic Network's filter.  I have the Muon and it made an immediate improvement, and does not have to be plugged in, which I find a big advantage for all the possible noise, switching power supplies, and space and clutter.  

I also upgraded to a Silent Angle Bonn 8 switch.  This was less impactful for me. It is available as I have just upgraded my switch to a JCAT M12 Gold which is amazing a clearly an upgrade, but much more $.

Ignore the naysayers.   Let us know how the fiber sounds!

So Wednesday my Amazon delivery arrived. I unpacked the two FMCs, fiber cable, LPS with its two extension cords. Connections were made easily except that the extension cords that amazon bundles with the LPS did not fit the input jacks in the FMC. Bummer. Luckily, the LPS provides one and I happen to have a spare.

I powered up the system and and queued up my list a test songs that I'm very familiar with but due to the amount of times I played them no longer enjoy. I checked my DAC and its white LED  light is lit indicating it is receiving signal from the Lumin. Stting up the fiber was a success. Very easy to do BTW.

Before i pressed play, I did notice an eerie feeling as if something was not right. It was a silence that i could "feel" if that makes any sense.

Anyway, I pressed play on the Stone's " Cant you hear me knocking" and that guitar rift blasts out of my right speaker. Audio Physic speakers have a reputation of " disappearing" but this was different.

This was special . I listen thru the whole song, Enjoying it as if I was hearing it for the 1st time. In a way that was true. Hate to use this cliche but I was hearing deeper into the mix. Hearing things I've never noticed before. Loving it. Track after track of songs that I enjoyed at one time but now were reborn.

I Did not experience any glare or glassy sound that Paulie Walnuts experienced :^)The bass did thin out a bit but in a good way for me.   

If you enjoy detail, look into fiber. I can understand some may find it thin sounding.

No bloom or warmth here.

Honeymoon period? Maybe. I have until January 31st to return

Lowered noise floor is likely the first thing one will notice with insertion of fiber, this will generally be an objective  finding. If one is comparing to an optimal ethernet setup it may be difficult to discern a difference here. With my present streaming setup I can have both optimzed fiber and ethernet chain. At present I'm most enjoying optimized ethernet from ISP through streamer ethernet output to Sonore OpticalModule, so fiber from the module to dedicated streamer(OpticalRendu). Full ethernet chain using custom streamer minus the Sonore fiber components not quite up to the fiber setup. I have one further ethernet upgrade available to me that could change the equation.

At this point, based on my own experience and many others, I'd suggest both routes are capable of delivering a top flight streaming experience. One should evaluate comparative reviews of these two modes with a critical eye. One will find vast majority of these comparisons  between optimized and non-optimized modes of bit transmission.