I just received this device, along with a FiIO X5 to replace my now discontinued iPod classic.   At first I liked this device - smaller, lighter than the FiIO, although only 1 slot.   Shipped without any user guide, however.   I formatted my 128 G SD card and inserted it, connected it to my mac.   I used doubleTwist software (which I had successfully used with the FiIO, and let it sync overnight.   I came back and and the device seems to think I had no music. I plugged the USB cable back in, and the files where definitely on the card.  ...