Improving on the stream of a combined streamer dac

What is a Schmann generator?

You might try a DDC as I and many here have found it can provide very significant improvements in streaming performance.  I bought a used Denafrips Iris for $400 and it made a big difference so this may be something you can try that won’t break the bank.  Best of luck. 

Good advice so far. I would invest in the best Ethernet filter you can afford. I have had good luck with the Stack products, having recently upgraded from the Smoothlan to the Regenerator, I can vouch for their effectiveness. I run mine before my server, but you can try moving it between the server and streamer. If you are looking for a Canadian Ethernet cable, I like and have the Audio Sensibility OCC silver cable. WireWorld is a great option as well.

While it may have only a small effect, a good shielded power cable, and maybe power filtering if you have a noisy line, might make a difference. Noise is the enemy of digital. 

Sounds like your electrocompaint is a bad product....Are you outside the return window? If so, quietly sell it off and cut your losses.

I recently (foolishly) compared the streamed sound of my Electrocompanient

ECM 1 Mk II to internally stored digital downloads on the same ( ie not stored in my Small Green Computer server). I was surprised how much better the downloaded files sounded.  

Not sure why no one has mentioned this, but the culprit may be Roon.  Many have said that the same stream through Tidal connect vs Roon, the non Roon stream sounded better.  I haven't obtained Roon for this exact reason.  From what I understand, it has to do with how the file is encoded in Roon and how the streamer handles the encoding.  Not sure if anyone else has had that experience but that could certainly explain why you're getting sub par streaming compared to downloaded files