I've been a big fan of the Squeezebox system from long before Logitech purchased SlimDevices who originally made the device. I keep my music collection in FLAC format on my computer and can easily access it from my Squeezeboxes that play the music synchronised all over the house. As an added bonus, the Squeezebox also supports streaming a lot of different internet radio stations. What it doesn't support, however, is playing arbitrary audio output from your computer.