We named this cable Ground Breaking USB for a very specific reason - it breaks the ground connection between the source (e.g. computer) and destination (e.g. DAC).
By doing this is minimizes the noise and interference between your computer and DAC
To use the ground-breaking USB cable you need a DAC that does not need the USB power to be connected.. If a DAC does need power, it also needs the ground, so you cannot disconnect this.