I covered this in another post but to be able to play wav files in froyo you must turn off stagefright. My solution was to create a script to enable and disable this option. To do this download gscript lite or pro (if you like it). Then create two scripts, label one "Stagefright on" and the other "stagefright off" below I've written the scripts for each of these. Now that they are created all you need to do is run stagefright off before listening to your wav file. You can even leave stagefright off it won't hurt anything but you'll take a hit in the performance according to the benchmarks like quadrent. I hope this helps I know I was bummed when my vm files wouldn't work in froyo.
"Stagefright off" = "setprop media.stagefright.enable-player false"
"Stagefright on" = "setprop media.stagefright.enable-player true"
Oh one last thing you must be rooted and have S-off installed for this to work. Non rooted owners are out of luck till Google provides a fix if ever.
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