Originally Posted by tehstup
you are wrong. the phone uses the id pin to tell what mode it is in. a different resistor on the pin means different modes. there is a USB mode, a UART mode and an Analog mode. If the phone isnt programed to recognize the different modes, it wont work. phones that dont have an external headset jack are programmed to switch between USB mode and Analog mode.
I know how usb otg works, I'm saying the Droid's usb port isn't wired for sound! There has to be a circuit between the audio dac and the usb port. The only phones with that capability are the ones without a real headphone jack.