@soix I am using Windows 11 and the Douk is plug and play. I connected the Douk to my Pegasus using cheap AmazonBasics HDMI cable and it worked like a charm. The Douk will appear as XMos XS1-U8 on your Windows so make sure you select it as the system output. Roon infuriatingly does not use it by default and I have to manually enable it again after each Windows update.
@tjag I used the I2s with my Pegasus and I had to say the difference with the USB input was minimal if any, but I still used it anyway because with the Douk I could actually adjust the volume in Windows. Without it I had to reach to my amplifier volume knob. With my Lab12 Dac1, the difference between with USB and Coaxial is more significant, probably the coaxial implementation is more well thought out.