Genelec hardware volume controller 9310A / 9310B can be used for adjusting the sound level when the computer is detached from the GLM adapter. When this is done, the GLM adapter must be powered with a standard USB power supply. The voltage output of the USB supply is 5 VDC. To use an external USB power supply, remove the USB cable from the computer and attach the cable to a USB power supply, as shown below.

8300-416 GLM adapter requires 180mA.
8200-416B GLM adapter requires 500mA.