Doesn't play m4a?

Been reading up a lot lately on these sansa Players and finally decided to get one. I planed to use it at work and listen to podcasts, but now I’ve discoverd that it’s apparently not compatible with m4a, witch several of my podcast formats are in. Anyone know wich one of these players support that file type? Or the best one to use rockbox with?

Clip Zip.  But note that there sometimes can be issues with the files there as well, depending on the encoder that had been used and especially with long files.

My sandisk clip sport is not playing my M4a music files right way it tends to stop playing with in 2 seconds on the song track then skips to another song.

please help me.