That little SR grounding box works well in my setup too. As for the ethernet side, it seems you have taken all the steps to clean up the noise that is carried by ethernet cable. Once I thought I had taken reasonable steps to clean up the ethernet, it occurred to me that noise still travels via electrical lines and although my dedicated outlets help, the hifi is powered by what is essentially an electrical circuit.It has been a while since I posted on this thread and have a few things to add to the mix. Six months with the MU2 and I can't imagine a legitimate need on my part to look for another dac/streamer for my digital only system. It is nice to have a piece about which I don't need to worry or consider changing.
My first attempt to clean up the noise was to install a grounding rod outside the house and have the electrician run two dedicated "home run" lines for stereo equipment only. I use the SR small passive grounding box that feeds into a wall unit. These two things brought a level of blackness or dark background not achieved by anything else to that point. Having heard it, I would never go back.
I then considered going down the Network Acoustics Tempus/Muon Pro filter and cable road. That was about a $6,500 toll. Instead, I went down the Dejitter It Switch-X and Wifi-X road through GTT Audio. This was a $4,350 toll. These latter pieces create a separate "clean" internet access point. Again, having heard the "before and after" I would never go back. At this point, if there is more noise to remove or darkness to achieve—I don't know how to gain it or if I could hear it.
In a separate room from the hifi, there is a router, TV and TV box. All are polluting devices by nature of their SMPS. Although they are all powered by a balanced power unit, a few experiments told me that noise on this common line was traveling back to the electrical panel and polluting the dedicated outlets too.
I'm trying one of these in the outlet that also powers the balance power unit: https://www.akikoaudio.com/en/products/product/akiko-audio-triple-ac-evolution-u-s Although it has only been a few days, I'm surprised by the clarity it brings. I can try it for 45 days but I already know it is staying. Once it has been in place for a month (burn-in time according to the manufacturer), I'll try it with the outlet that powers the Shunyata distributor.