A Samsung Galaxy S III with a Micro-A plug inserted can operate as a USB host (i.e. a USB host-enabled Samsung Galaxy S III can interwork with a standard USB peripheral like a standard USB DAC iBasso D12).
A Samsung Galaxy S III with a Micro-B plug inserted will operate as a USB peripheral.
Micro-A plug: The ID pin shall be connected to the GND pin.
Micro-B plug: The ID pin is not connected.
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Android phones and USB DACs