What signals ate you trying to send on the Jack and XLR outs? The Main Output Jack and XLR outputs will always send the same signal. If you are trying to send different signals like DI or Delay/Reverb wet only you need to use Direct out and/or Monitor out along with the XLR or Jack for main outputs.
I've got it to work now, but the volume is extremely low at the moment. I can't seem to find out why exactly. (I've checked the Fosusrite software, but everything seems alright)