I am pretty sure this depends a lot on your server configuration.
WAVE format (in pretty much all of its flavors, including Microsoft and RIFF) has a field with the data size on top of the data block. This is read by the audio
element especially if the preload
attribute is set to blank, auto
or metadata
Thus, the web browser making a request for such file might only request that many bytes and then just close the connection. There's nothing in the API description that says it'll read until actual end of file is met.
One thing that comes to mind, though, is registering on the "end" event. Then, according to this answer, you should be able to start playing again, seeking to the position you've ended on. The server should start streaming the data from the position you need. If it doesn't work directly, I'd try reinserting the audio node with preload="metadata"
so that it could read the updated file size.
Another, perhaps simpler thing would be hacking the file size to be something absurdly big. With some luck, it might "just work".