When I extended the license of irrKlang
to make it possible to buy the library for some more advanced features, I decided to use a License model which is not very friendly for open source and free projects, although one of my bigger targets was to support those projects just like with Irrlicht.
I'll change the license of irrKlang pro with the next release next week to something like 'all features are free for non-commercial use', everybody should be happy again then. So now, you can stop the email bombardment asking me for a change like this. Please :)