OK, I've done it
It works like a charm now... I just followed the steps from the following link: http://beranger.org/index.php?page=d...yp-u3-j-linux-
Download the ftp://celtic.no-ip.org/pub/Samsung_YP_U3/DFU.ZIP
, unzip on Windows, and follow PDF instructions. First flash will fail, but it's only the preparation one. After that, you just flash it again, as instructions say, and that's it. I even thing it has better sound now, although it may be only a placebo. When I start it on, it says "ver. 1.10 WA" Happy flashing!