Sbooster Vbus2 Isolator
These days, when you connect a USB external hard disk drive to your laptop, you don't need a separate power supply for the drive because the USB connector supplies power as well as transfers data.
But your USB DAC is already plugged into a wall outlet, and doesn't need the USB-supplied power. So why not remove that polluted power from the data signal path?
The Vbus2 disables the power on the USB output of any computer or streamer, allowing only the data signal through.