Is the D2 USB isochronous or asynchronous?

The D2 uses "adaptive mode" in it's USB receiver. This means that the USB receiver (Texas Instruments 1020B) will keep track of the data coming in from the computer and adjust so as not to miss any incoming data. Due to the nature of the wireless link, the data then becomes asynchronous before arriving at the Receiver. Thus the D2 acts as an asynchronous USB DAC with the added benefit of being 24/96 bit-perfect wireless.