I have used the BabyFace Pro analogue inputs and found them to be quiet (albeit that was with consumer audio gear and home-made RCA-XLR cables).
This might be a ground loop. Can you try running your laptop unplugged or the CP33 with batteries?
If you are in the US, some homes use an odd 2 leg system. If you can find an extension cord to plug ONE component in a different room that goes to the other leg on your fuse panel that might work. There are other solutions to ground loops you can search for.
Check to make sure your cables are properly made using a multimeter and the following guide. http://rane.com/note110.html
The BabyFace user manual guide has some tips also on proper cabling:
"The Babyface Pro has two analog microphone inputs that can operate as line inputs with levels up to +19 dBu, when set to 0 dB gain and PAD active. The electronic input stage uses a servo balanced design which handles unbalanced and balanced signals correctly, automatically adjusting the level reference.
When using unbalanced cables with the XLR inputs pin 3 of the XLR jack should be connected to ground. Otherwise noise may occur, caused by the unconnected negative input of the balanced input. "