If you are not familiar with USB audio device, please read the FAQ topics on "What is USB Audio and how do I configure Windows or Mac computer for USB audio and the DAC ?" and "USB Standard and Ports"
The standard USB audio cable that comes with your iOS or Android device can not be used to connect the DAC. You will need a different cable that treat the iOS or Android device as the host, and the DAC as the client.
USB Audio has always been supported by iOS. You can use Apple USB Camera Adapters to import photos from your digital camera. You can also use Apple USB Camera Adapters to connect other USB devices to your iPhone, iPad, or iPod touch. If you're using an Apple USB 3 Camera Adapter, you need an iPad with iOS 9.3.
Some USB devices need more power than your iPhone, iPad, or iPod touch can provide. If you connect one of these types of USB devices, you might see an alert that says “attached accessory uses too much power." Try one of these steps:
Prior to version 5.0, the support for USB audio is spotty. Some device manufacturers do a better job than others. In general, Android OS 4.1 and above provide support for USB audio device. If you have doubt, check with your device manufacturer or search for help online. Please do not ask our support staff. In general, similar to iOS device, if the DAC is connected and functioning properly, the Android OS will send the audio to the USB port. There is no need for any system configuration.
We strongly recommend USB Audio Player PRO for high resolution music playback.
Similar to iOS device, if your USB device consumes more power than allowed by Android device, you will need to power the USB device. If you are technically inclined, here's a useful article: http://source.android.com/devices/audio/usb.html
Powered USB DAC
NuPrime DAC-10/10H, DAC-9, IDA-16, IDA-8
Externally Powered USB DAC
How to connect to a powered USB hub - you will need a USB Type A to Type A cable for connecting the Android USB OTG Cable or Apple Camera Adapter Cable to the USB hub.