The best way on a Mac would be with iTunes, (nice interface, sorting etc...) encoding with a high bitrate or even apple loss-less, and then maybe an airport express, which gives you the convenience of the wireless!
http://www.apple.com/airportexpress/
Also there's a cool app called airfoil which can stream audio from any app to you airport express (as out of the box it can only do itunes)
http://www.rogueamoeba.com/airfoil/mac/
Although if the audio quality isn't good enough from the airport express then you'd be looking at an external sound card like any of these
http://www.turnkey.co.uk/web/searchA...ces_(Firewire)
this would guarantee you high quality sound as it would bypass the internal sound card completely. You can switch between different sound cards, if you have more than one, in "Audio MIDI Setup" in the Utilities folder (in your Applications folder)