Hey OP,
If you put a noise source on the "clean side" of a power conditioner you can dirty the power you just cleaned up. Of course, this depends on a lot of things, including whether or not there are multiple filter banks or not.
Regardless of brand or $$$ spent, you need to make sure your cables are shielded, which many expensive brands are not. You can test this out somewhat by moving the cables around. Usually when an interconnect is acting as an antenna it’s relatively easy to hear/see the response when you push them around.
iFi makes wall wart replacements which are much cleaner and create less noise into the power line than your average wall power adapter.
If at all possible, I'd move your mesh receiver as far as possible from your stereo. Ethernet is REALLY good, so even if you run 10' of it so your wifi units are on the other side of the room it's worth it if it keeps the rest of your system quiet.