Although it has a lot of features and looks promising i'm a bit disappointed in compatibility and design.
metaudio comes with integrated third-party software. For client-side audio playback, it either uses SoundManager 2, or its own audio player implementation, written explicitly to improve upon the sluggishness of SoundManager 2 and address some of its robustness issues. From the review, it is not clear which browser interface is to be meant; the metaudio demo site uses metaudio's own player implementation. Furthermore, compatibility is a complex issue, often involving aspects not related directly to the extension. It is best to get in touch with the developer, where there is a possibility of mutual interaction.