That's a rebranded BLACK DAWN 1.0, with the playlist text changed to match the overall scheme (I never understood why those were left to the default colors originally, it's like four lines in a text file!) and a couple buttons changed as well. I've used the original for an eternity. Great skin.
I just checked and my current skin is just "Winamp Modern" (I'm lame, I guess), and I'm using the "MonoDark" color variation of that one. I keep it in the top right of my monitor, that's why it's shaped like a '7':
https://mltshp.com/p/12I7T
https://mltshp.com/p/12I7T