Conclusions
We can easily demonstrate that devices like JitterBug cannot work. USB is a high-speed bus. You cannot filter it without causing the data to be corrupted. So any filtering that JitterBug performs there must be well into Megahertz region and hence outside of audible band. Since data transmission to a USB DAC is highly reliable anyway, filter does no good. As to filtering of the USB power, the DAC itself has a regulator and filter of its own. Adding the tiny bit of filtering JitterBug has is like spitting in an ocean and expecting its level to rise.

Please save your money folks. Give it to Charity. Go have a great dinner. Anything but rewarding people who build these useless devices that attempt to solve problems that don't exist.

AudioQuest JitterBug USB Filter Review - AmirM