Micket has updated Oldplay for GP2x. Oldplay plays plenty of older but also news audio formats. You may consult the readme.txt for a full feature list.

Changes:

* Fixed bug where volume was not changed until song was playing
* Increased max volume (per request). The difference between low and high is now
VERY large. Hopefully everyone will be satisfied.
* Mods are back at stereo again (per request). Since there is a stereo-mix feature
those who want mono should use that.
* Turning off the screen might work on F200 now

http://www.gp32x.com/board/index.php?showtopic=41276&view=findpost&p=597007