If you want different music each area would have to be a separate zone so it sounds like you need a receiver with powered main and 2nd zone and a 3rd zone unpowered line level out for a wifi transmitter for the upstairs speakers.
A better solution would be to use Sonos. Much more straight forward to operate, Great free easy to use control apps for ios, android, kindle or computers. Works with almost all streaming services and plays any music files on the network.
You could use a combination of ConnectAmps and Play speakers to set up the house audio. Might be a bit more price wise but people pull Crestron systems out of mansions and replace it with Sonos for a reason. It works and works well.