Apologies, I gave bad advice 
In the attached document I left the JS action in place, but I created an off scene rectangle containing this:
<audio id="allTieInnerHTML" height="100" width="400" preload="auto">
<source src="${resourcesFolderName}/AllTie.m4a" type="audio/mpeg">
</audio>
The ‘preload’ property in combination with the preloaded option in the resource library should result in immediate playback when clicking the button.
You can see the preload in action by watching the Network tab in Chrome’s developer tools.
preloadAudio.hype.zip (115.5 KB)