Re: Network audio card
The best solution that I have found is to store music on a network attached storage, then I can play it from any computer on my network. I use iTunes to play from the computers, and a buffalo linkTheater network media player to play music from the NAS to my home theater system.
You could configure a folder on one of your computers to share the music stored there with the rest of your network. That way you could access the music files from any computer on your network.