The only noise it makes is from its single hard drive. The fan never kicks in on mine (unit never gets hot enough to activate the fan unless it's 100 degrees in the room with it).

The hard drive itself is reasonably quiet, but not 100 percent silent. It's only audible at the quietest music listening levels. Assuming you're even in the same room with the thing, it's mainly a server for me, the only time it gets used for direct in-the-same-room audio for me is for working out on the treadmill, and at that time the music is cranked.