A couple years ago I threw together an audio engine for a school project, since I was frustrated with the lack of audio engine's that just played a sound without having to jump through hoops to do it (This being a primary reason why I hate XNA). Several months ago I revamped the entire audio engine into something that was stable and capable of properly doing things like seamless looping, volume, multiple playbacks, reading audio from internal memory buffers, etc. After learning that a friend of mine was still using my old audio engine because it was so easy to use, I decided to make my now-proper audio engine public and open-source, and renamed it TinyOAL. This stands for Tiny OpenAL Audio Engine, and to give you a grasp of how tiny it is, you only have 2 classes to bother with - the engine, and a class for audio samples.TinyOAL v0.9.5
It's written in C++, but there's also a .net wrapper available. Right now the only reason the C++ code isn't platform independent is because it only knows how to load DLLs using the windows functions, so as soon as someone who knows how to program Linux finds it, it'll support that too.