Sounds like you need an MP3 player for Mac.

SoundApp 2.6.1 is Freeware that is said to play any audio file.
Go to www-cs-students.stanford.edu/~Franke/SoundApp/

GrayAmp is also Freeware and is a very basic player.
Go to www.digithought.net/software/grayamp/

I use SoundJam, which I love but Casady & Greene stopped production of it on 6/1/2001.

You can also check out www.applelinks.com/mooresviews/players.shtm
8 different Mac MP3 players get reviewed there.

Good Luck