WiFi2HiFi acts as if your PC has an additional audio output socket. Thus you will be able to use the software signal that you use to play music and send it via this program to your mobile device, be it an iPhone, iPad or iPod touch.
Once you have launched the application you will only have to configure the proper IP address to be able to connect both devices. From them you will be able to control playback parameters, such as the volume.
If you're a user of any Apple hardware, WiFi2HiFi is a very good application to listen to music by means of streaming. Play your PC's audio on your iPhone, iPad or iPod touch and enjoy your music collection remotely.