What was the procedure here? I don't quite understand?
When you plug-in a USB Audio Class 2 (UAC2) device, windows won't recognize it, but it should tell you that something was plugged and was not recognized. Did you see that at all?
Then, when you want to install the specific drivers, from my experience, most of them actually need that the DAC is connected to the PC. I don't know why there's such a requirement, but it is what it is. The Xmos, USB-32 and Concero drivers require that the DAC is plugged in before installation.
The only one that was happy without the DAC is the Amanero Drivers for the Ciunas DAC/Converter. So you can install them right now: http://amanero.com/drivers.htm