If you are providing a service it should be accessible. If you are using a fancy API that is not accessible (yet) you should provide a fallback, or—better yet—use the fancy API to progressively enhance the service.
If, however, you are making a fun little game which relies on Web Audio API, and there is no point in playing the game without headphones, then your good. The line is pretty obvious in most cases. Or at least you—as a web developer—should know it when you see it.
If, however, you are making a fun little game which relies on Web Audio API, and there is no point in playing the game without headphones, then your good. The line is pretty obvious in most cases. Or at least you—as a web developer—should know it when you see it.