I have a program called free m4a to mp3 converter on my computer I use to make itunes files mp3s if I really want them on my phone (or to send them to other people... cough cough...). I think it works with even drm-ified itunes tracks, I've never received any error messages, may be worth a shot if that's the issue. It'll take a while to convert tons, and then you have everything saved twice, but if you just move it to your phone and then delete them off your computer, it could work? But it sounds like your issue is organization, not the file types. Have you tried doubletwist? I'm afraid I don't know much about airsync, but that could be an option for you? And google music has a syncing/cloud system, or did a couple years back when I gave it whirl.