Airplay works very well for streaming music. If you have that functionality built into your AV receiver, then you're good to go assuming that you use iTunes as your front end for your music. You simply select the wireless device you are using in the lower right hand corner of iTunes.
You have your music ripped in flac/wav and so you'll want to convert it to apple lossless to play (keep a back up in flac/wav).
The only other problem is that you need to use iTunes as your front end. It's a pretty good front end so that's not a big problem. Your AV receiver may be able to handle music streaming services such Pandora natively. If not, this software should do the trick:
Rogue Amoeba | Airfoil for Windows: Wireless Audio Around Your House.
In any case, airplay is free so you should try it before investing in a streaming device.