That’ll work just fine. You can just use the USB output port (5V/2.4A) and a USB type to micro USB cable like this:
You can also achieve the same thing using one of the many USB powerbanks available (like below):
To get the isolation from mains power though (like during critical listening) you don’t want to be charging (connected to AC mains power) at the same time as listening. So just run off the battery with the charger unplugged.