In 2021, as soon as Windows 11 was released, I decided to install it and noticed that the sound quality in my headphones had changed significantly, in my opinion for the worse. I often listened to the same tracks using the Philips SHP9500 + Meizu HiFi USB Dac combination. The sound became more "muddy" and less detailed, with a narrow soundstage pushed forward. I also noticed that if I set the maximum sample rate on Win 11 (in my case, it's 352/384khz), the sound changes slightly (I'm not sure in which direction), but the bass becomes more responsive, and the high frequencies are more defined (this is not the case on Win 10). I thought it was a problem with my computer, but no, I tried it on two different PCs, and the situation didn't change. I went back to Windows 10 and continued listening to music, occasionally switching to Windows 11 and then rolling back, hoping that something would change. I thought it might be a problem with my cheap DAC, or that the drivers were installed incorrectly. Another important detail is that if you set a high priority for the USB hub that is connected to the audio device in the GoInterruptPolicy program, the sound becomes more assertive, dynamic, and detailed (this did not work on Win 11). And now recently I got a new FiiO K7 DAC/amplifier and Hifiman Ananda Stealth V2 headphones with Openheart 16 core balanced cable. About 2 months I listened to music on Spotify on Win 10 and was enjoying the sound. Installed Win 11 and the situation repeated, the sound is just terrible. The wide stage narrowed and moved forward, the instruments decreased in size, the cymbals became not metal but wooden, the bass became more but it is not so collected and punchy. All the built-in "enhancers" and surround sound were turned off. I also listened to music through Foobar2000 with ASIO/WASAPI, and the sound was just as bad. I've returned to Win 10. Again. I wrote to Microsoft support about this, and they replied that they had changed something in the audio processing, but I still don't understand. I can't resolve this issue - what was it? Maybe the audio is actually better on Win 11, but I don't know. Please help me find the answer.