OK, so after my last post I figured, what the heck, why don't I actually just look at the source code that won't compile. The problem is pretty obvious: in the 3 header files AudioMp3.h, AudioOgg.h and AudioWav.h, the namespace/class qualifier is used inside the class declaration. AFAIK, this is simply broken code that no compiler will swallow, but who knows perhaps there are C++ compilers out there that think it's all good. Anyway, by simply deleting the qualifiers from the members in each of the three files, I got the code to compile cleanly. What's strange though, is that this broken code came straight out of a Qtella download. Oh well..