[willndmb]

where did you get protected m4 files?
all the ones i Dled you could convert to mp3/wav/aiff no prob

can't really answer your question but i know a way around it if worse comes to worse
burn them to a disc and rerip them however you want, of course a Rw would work good because i assume you don't really want them on disc since you asked about playing them in another audio program