I have been using a device from Roland that I can plug into the USB port of my laptop running windows 7. This converts audio signals from the soundboard via RCA connectors to the USB input for a computer.
Of course I know its not compatable with android. There are recording programs available for android. Is there a USB device to do the task of getting an audio signal into my Acer 210 10" tablet running Android 4.1 jellybean.