Is there a fan in the sirocco?

You could try lowering the voltage slightly, but if you go too far, the device will obviously stop functioning.

Also, to reduce the noise make sure the Sirocco is in a relatively cool location. Being inside a hot cabinet with a cooking AV receiver will cause it to be noisier than usual.

Yes, mine also buzzes in a fairly distracting way. It is not a very loud noise, but as one poster mentioned, it is a noise I could hear from anywhere in the room, even during the daytime. Considering I got this as an "audiophile" type device needless to say I am a bit disappointed :P
Since I am in the UK a return would be fairly difficult - any suggestions for reducing the noise? I guess the only thing I really have at my disposal (other than making a padded box to put it in) is to vary the drive voltage a bit...

Personally, I can only hear the noise from within two feet, and when I am intentionally listening for it. Of course, this varies from person to person, as well. We did have one return due to noise, so it's possible that some units are louder than others.

Wow...fast response.
Can you define "very quiet" ... do you have a sound level measurement of it? I can hear it, faintly but pretty distinctly, anywhere in the room. I have a computer in the same room and the drive noise (a "quiet drive") is about as loud. I'm pretty sensitive to equipment noise so I might notice where other people don't, but my wife hears it also and she is pretty regular in how much she notices.

Hi,
Nope, there are no fans in the Sirocco, but there is some low-level thermal noise from the SoC that is audible if you are very close to the device. This should be very quiet, and you shouldn't be able to hear it unless you are right beside the Sirocco.