I recently purchased and recapped some old Technics speakers and was getting a fantastic sound out of my system despite running an old Asus Xonar DX sound card. I run through an old Rotel amp. Then everything went backwards, harsher trebles in particular. I was just on the point of opening up the Technics to check my soldering, when I checked and found that Windows updates had reinstalled all the old sound devices and drivers that I had disabled - Intel, Nvidia and Realtek, all now enabled alongside the default Asus device. Realtek just kept on reinstalling, starting whatever. Windows updates had put Realtek back as a start-up service. I managed to disable this and the device in device manager and finally managed to stop it loading.
Despite the Asus card being the default audio device all along (Wasapi in MC), I'm now back to perfection. I wouldn't say I have goldenears, but the difference is clearly noticeable, different soundstage, all harshness vanished, less of an artifical separation. The Realtek driver seemed to have been getting in there somehow, despite not being selected as an audio device. I presume I am now using the native Windows 10 audio drivers.
So pleased that I have got my sound back. I thought I would post.