Advice on Improving a Wifi-Mesh -> Ethernet Setup?

@david_ten I really appreciate your input, and I hope it didn't come out the wrong way. I have isolation bases similar to the Acoustic Revive TB-38H for my main components, and now I intend to get another one for my Orbi.  

I know this may sound crazy, but recently I upgraded my "real" router (one that connects directly to the modem) from a budget TP-Link to a $400 Nighthawk. And the change in SQ was not subtle. I find it mind-boggling, as it's not even physically connected to the streamer network, only the Orbi router. I'm tempted to power it with a quality LPS just to see what happens.

Are you using a stock/generic DC cable? If so, a custom aftermarket DC cable may deliver surprising improvements. Custom DC cable + grounded LPS + isolation/resonance control for the LPS. Trifecta.

I am! I can indeed do better than the stock DC cable. I should probably also give the LPS a better power cord.

@serancien   Not at all. 

I recently went from the older AC3000 Orbi Pro to the current AX6000 Orbi Pro.

I made the change for non-sound quality reasons. Every aspect of the chain was exactly the same, except for the old router/satellite being swapped out for the latest router/satellite.

The difference in sound quality was significant.

+1

I can indeed do better than the stock DC cable. I should probably also give the LPS a better power cord.

I have been moving some things around just to find out what will happen so may move my HD Plex LPS over to my router.  I have a smaller ifi filtered power supply (I do not believe their power supplies/adaptors are linear but they are filtered) that I can use on the Gigafoilv4 and the ENO doesn't need power.  I am currently using the HD Plex on the Gigafoilv4 because it is closest to my server.  As mentioned, the results of any of this have been so subtle as to make me wonder whether there is any effect whatsoever. 

Things that do make a noticeable difference include the upgrade I just made from a Mojo Audio EVO B4B21+ DAC to their EVO PRO DAC (a positive move - slightly better resolution and spatial information), and also I have compared running USB directly from my Mojo Audio Deja Vu server to the DAC vs. running Ethernet from the server to a separate Roon endpoint (either Metrum Ambre or Bricasti M5) and then AES/EBU or S/PDIF into the DAC.  The USB sounds better (slightly richer, tonally bolder, and more dynamic) but the server uses the well-regarded JCAT USB CARD XE so maybe no surprise there.