I use an "Airport Express". It is hidden behind my BeoSound 9000 and plugged into the AUX connection (via the audio jack on the airport express). All of music lives in on an Mac Mini that "shares" its iTunes library. Once the Airport Express is configured, it shows up in iTunes as an "alternate output" in the lower right hand side.
So I set the 9000 to the max possible volume that I want, then bring up itunes on any computer/laptop in the house, select the Airport Express in iTunes, then stream music to the 9000. Then I can control the volume via the volume slider in iTunes. It's easy and sounds great. Plus I get the advantage of my full music library, not just what's on my iPod.
You can add multiple airport express units (in different locations) and stream to multiple systems at the same time.
You will need:
1 wireless hub/router, it does not have to be an Apple Airport.
1+ Airport Express units
1 PC/Mac with iTunes installed
1 B&O AUX to Headphone jack cable
NOTE: To configure the Airport Exress, you may need to use a Mac. I am not certain and do not own a PC.