You could setup a home network to stream music to your receiver through an Internet Radio/Network Music Player, like these:
Internet Radio | Grace Digital
This one here,
Tuner Wi-Fi Radio Wireless Radio & Media Streamer | Grace Digital, has the best quality sound (optical), though not the best user interface. However, they have an app for both iphones and droids that greatly improve the interface.
If you have a home computer(s) I would keep all the music, you and your wife's, on it to simplify things. You probably already have your music backed up on a computer.
There are other brands out there too like Logitech, Denon, Cambridge, Sangean, that have similar type devices for varying prices.