Ok, let's go over the basics then.
First of all, you need to have perfect playback through DS, WASAPI/ASIO/KS are of no consequence until you have glitch-free playback. Set the buffer to something between 800-1600ms, try different USB ports, go to Device Manager and disable power management for both the ports and the device, as well as going to the Windows power settings and disabling selective USB suspend.
Also, do those tests with no ethernet adapter enabled. And do post a screenshot of your DPC latency, measured through Thesycon DPC Latency Checker. Post a screenshot of your DPC latency with ethernet adapters disabled and another screenshot with ethernet adapters enabled.