1, rectify the gapless function;
2, an improved EQ function;
3, user replaceable wallpaper. Wallpaper can be replaced by adding a 320*240 pixel wallpaper.png into the DX50's root folder.
PS: the sleep timer has also been fixed.
Yes, despite my boondoggles comment (which is true), it is a fine addition. I am going to have some fun with wallpapers. I might even make a Rockbox theme - the next best thing to being actually able to Rockbox the DX50.
I've found 1.2.7 here: http://ibasso.com/download/DX50Firmware_V1.2.7.zip
Everything works well.