Regarding Windows 10, if an audio device is running ASIO drivers and is still assigned as "Default Sound Device" and or "Default Communication Device" then Windows still mucks with SQ. The only solution I have found is to make sure those two device assignment point to an unused sound card (present in the system, but unused by me). A remaining problem is that Windows will sometime reassign the two default devices to the most used sound device after a Windows update. WASAPI EXCLUSIVE mode seems to work more reliably in that regard. I assume it is Windows sound engine that is causing the problem, I have seen it resample PCM ASIO streams in the past when I had a sound card that displayed the received sample rate and bit-depth. Whatever Windows sound engine is doing and regardless of what it looks like on an FFT, with my best dac the difference in sound is noticeable. There have been multiple occasions when I have started troubshooting the dac only to find out Windows had reassigned the default devices.