It isn’t loud, but it is loud enough to be heard even though I have my pc and laptop running just next to it.
The noise is at around 11Khz and then again at 22Khz, 33Khz and 44Khz and can clearly be seen at this spectral display:

I made this recording of the noise to figure out more about the problem. Around the middle of the recording I turned off the XITE and the noise stops. The noise returns when I turn on the XITE again, so there can be no question that it is the unit itself that is producing this noise.
The noise isn’t present if the XITE has been turned off for a while, but after a few minutes it becomes audible.
You can hear the recording here:
http://www.itu.dk/people/petal/planetz/XITE-noise.wav (33MB, 96khz/24bit)
I asked SC if they have experienced any similar problems – but I have received no answer yet.
Have any of you XITE-owners out there experienced any similar problems?
And does anyone have an explanation to what could be producing this noise and if anything can be done about it?
Cheers,
Thomas