Let's cut to the chase: I didn't want to use batteries (I'm cheapskate, what can I say), so I thought I was being smart when I tried to use the USB port to power my Zoom G1X and my Zoom B1.
Alas, it didn't work as I expected. The USB (especially when used with a charger but even using the computer port) produced a lot of humming noise.
Holding my breath, I ordered the official adapter. It was incredible relief to plug it, turn it on, and realize there was no noise at all! Perfect, exactly what I needed.