ADAM Audio D3V pops whenever it connects or disconnects on its USB input. Switching to another device, unplugging, or plugging back in sets it off.

The fix is to take the D3V off USB before the connection changes:

1. Press the volume knob twice. The ADAM Audio logo turns from cyan (USB) to green (Analog).
2. Now do what you came to do: switch devices, unplug, plug it back in, etc.
3. Press the volume knob twice to return to USB.

Turning the volume knob all the way down beforehand also stops the pop, on both the disconnect and the reconnect:

1. Turn the volume knob anti-clockwise all the way down.
2. Make your change, as above.
3. Turn the knob back up to listening level.

The listening level has to be found again each time, but otherwise it works essentially the same as the input switch method.

The problem, which I can only identify as a firmware glitch, stems from D3V’s mute-override behavior. When a source switches, or a cable is disconnected, or reconnected, there will be some noise traveling up through the cable. Mute is supposed to block all output. For some reason, on USB input, it is still possible to make, though unpleasant, sound on the speaker. And as the glitch goes, turning the volume knob all the way down inexplicably behaves properly.

My D3V sits on the Thunderbolt hub of a Dell U2725QE, which a Mac shares over Thunderbolt and a Windows desktop over USB-C. Switching the monitor between them sets off the pop. Plugging the D3V straight into a computer was never an option. One cable from the laptop is the key to the setup. Why the speakers pop in the first place, I haven’t found out, and ADAM’s current firmware, 1.7, doesn’t mention it either.

One route I haven’t tried is taking audio from the monitor’s 3.5 mm line-out into the D3V’s analog input, which would leave USB out of the D3V’s path. It needs another cable and possibly means losing volume control on macOS.