Hey, I've had this issue with my Behringer x2222usb mixer since I got it, but just figured I was doing something wrong and forgot about it. Basically, whenever I use the usb output to my computer, I get this background noise that sounds like a very distant, but very present leaf blower. I couldn't figure it out, so I've just used the rca output going to a 3.5mm jack ever since. I'm under the impression that the Xenyx preamps in this mixer only work with the usb output, because the rca out gives me such an insanely quiet signal; so when it all comes down to it, I can either use the rca output and have to jack up all my channel sliders, or use the usb output and get this crazy annoying and obvious background noise. I need help if anybody can offer it. The reason I got this mixer was because of the usb output and the preamps... I just want to record. I can send anybody an mp3 of what this usb output exactly sounds like; keeping in mind this should be a totally clean signal, everything is muted.