@mojo771 I get high-res because my CXN is directly connected to the internet via ethernet. My phone is merely the control just like you but I control via my wi-fi connection. I"m not transmitting the stream from my phone.
"But to get hi-res flac from Tidal you have to use the Tidal Connect app on your phone, but can only play over a 2 channel amp / tower speakers by using wireless hifi."
This isn’t necessarily true. If the Vault is connected to the internet via ethernet and the Vault is a direct input on your system, then the app on your phone is still just a wi-fi controller. Tidal Connect streams do not travel through the smartphone or tablet on their way to the paired network streamer.
I’m not sure if the OP’s Vault is directly connected to the net via ethernet or not. If the OP Is connecting the Vault via Wi-Fi, then yes high-res is compromised.