I have an interference type noise in the background when recording with my Babyface (original). The level is relatively low, usually between about -72db and -60db at worst, but still seems excessive and is something I am hoping to reduce as much as possible. I am recording line-level inputs.

Here is a recording of the interference amplified to -15db:

http://www.reggae.ukboss.com/ampnoise.mp3

I have done the following in an attempt to remove the noise:

removed any unnecessary USB devices from PC
turned off internet and wi-fi
use some ferrite snap-ons on Babyface USB cable

None of this has really made any difference. Can anyone provide some help as to what I should do next?