So I just created an account here to add to the discussion.
I've once had a Xonar Essence STX for a full year without it happening. T'was a good sound card, alas there were some issues here and there with it stop responding and whatnot. I liked the audio quality I got, so when it came to build a new PC I went straight for the Xonar Essence STX 2 (or II).
I've had this card for just over a month and now, two times in two days, I've had this issue. Both were while searching through a Youtube video in the new player with HTML5 controls. Extremely loud, distorted sound that, upon ending, leaves a lasting tone just as described here. I contacted ASUS Support with the issue, this is what I got:
[Quote with ASUS mail reply stating they haven't heard anything of the issue]
That reply is extremely disheartening. I am dealing with a small case of anxiety and I definitely feel physically and mentally unwell putting my headphones on daily now. I really enjoy the sound quality it provides while staying inside the case of my PC, and I don't think any other sound card would do it for me, so there either having this, or going full, dreadful onboard sound.
To think nobody else has reported it "in the nordics" makes me a bit suspicious.. But people tend to go to forums for support, so I suppose they wouldn't get a lot of inquiries. I urge everyone with this issue to contact support so they can be made aware and maybe push Microsoft to look into their faulty software audio solution.
Sadface.