I'm rethinking whether "Handle" is a good term here.

Typically a "handle" is a pointer or integer identifier that is used to refer to some resource. This AudioPort on the other hand, is a ThreadableJob which processes an audio bus (and perhaps in the future, audio busses plural) rather than just a handle.

Some more applicable terms in my opinion would be "job" or "processor".

However, PlayHandle would also have the same issue of not technically being a handle. If this AudioBusHandle rename is for consistency with that, it may be okay for now.

That was what I was thinking. If we use Job here, we have to rename quite a lot of classes...