Hi Taikero,
You wouldn't happen to have a product number for that black-brown stain you mentioned would you? I had to match a black-brown Ikea desktop this year and it would have been a heck of a lot easier to have been able to buy their stain in the right color "off the shelf" rather than trying to mix my own. Thanks.
My experience may have been dated. Searching, it seems Ikea no longer sells stains, only paint and a select few outdoor stains. Still, I distinctly remember seeing it when I first picked up this desk several years ago, noting that if I ever scratched it or something, I could repair it with their stain. That may not be the case any longer. If so, sorry for the misinformation.
Searching for this answer, though, I discovered that Ralph Lauren Turrent Stair is a closely-matching paint color which seems to have a lot of fans...