When using the Wireless GO II with USB connectivity (using a USB-C to USB-C or a USB-C to Lightning MFI cable), the 'dB' button does not impact the output gain to the USB device, such as a mobile device or computers.
When connected via USB, the Wireless GO II act as a USB microphone and the gain is controlled by the recording software or DAW (Digital Audio Workstation) on the device.
The gain 'dB' adjustment on the Wireless GO II solely affects the 3.5mm analog output from the Wireless GO II receiver.