Well implemented DACs are built to work well with the normal range of noise from USB. Archimago
published Raoul Trifan's measurements from the different USB ports on several computers, showing quite how much variation there is even between different ports on the same computer. The DAC measurements on this site use an ordinary USB port on the PC running the software, not some special low noise port.
These measurements show how the same DAC measures when fed from a Pi, an Odroid SBC, and a Microsoft Surface tablet - the differences are similar to those you would get between runs on the same equipment.
There are some DACs like the Modi 2 that are sensitive, but this is obvious from the
measurements. The solution is to get a better designed DAC.
The other thing that's often incorrectly blamed on 'noisy USB' is the modern presentation of the 'ground loop.' The stray ground current used to come mostly from mains frequency sources, presenting as hum or buzz. Now the stray ground current can be modulated by computer activity (mouse movement, gpu activity etc.) so it sounds different, but the fix is the same, and not specific to the Pi or USB.