I recently upgraded my computer to a retina macbook pro. As unfortunate as a choice that it was, the designers of the computer neglected to include a 3.5 mini audio in port on the device, only audio out. I have been trying to digitize some of my records and I need an audio in. I have been trying to get my Fiio E7 to function as a line in, using the aux input, and running over usb. Does anyone know if this is possible with this device? So far it doesn't seem to be working, but I was hoping someone has a solution.