Plug & Play, if every USB audio-required component is functional.
It depends on your Android device: native USB audio (i.e. USB audio-enabled Android device) or eXtream USB audio (i.e. USB host-enabled Android device with the USB Audio Player PRO app available on Google Play store).
To work with an Android device, which is a legacy USB peripheral, a USB OTG adapter (i.e. pin 4 connected to pin 5 micro USB plug to standard A receptacle cable adapter) is needed.
A USB OTG adapter switches the USB OTG capable Android device to USB host mode:
Android device with native USB audio or with USB Audio Player PRO > USB audio out >> USB OTG adapter + regular USB cable provided by the USB DAC manufacturer >> USB DAC >> amp >> headphones
In order to be sure that the USB OTG adapter is functional (i.e. the pin 4 of the USB OTG adapter is connected to its pin 5, so that the Android device is configured to USB host mode able to interwork with a USB peripheral like a USB DAC), let’s test it with a simple USB peripheral like a USB mouse:
Android device >> USB OTG adapter >> USB mouse
A compatibility list of Android-based USB audio: