I'm not sure if it is really possible or likely to pass noise on via USB. But, USB carries more than just data. It carries power, which means that ground noise can be carried across the USB cable and if you have a lousy laptop or DAC, then that noise could make it into the final analog audio output. This may be noise that isn't present in any manner in the digital stream at any point, but is being introduced by the actual cable present between the two devices.
I've certainly seen many laptops which product noise on their own analog outputs when plugged into a wall, but when removed from the wall, that noise goes away immediately. I think computers continue to ignore audio quality as a primary consideration in design and it is left to consumers to find out where those failings may be.
