I feel that the Stop action of the Audio object isn't quite fit for games because it abruptly cuts off the waveform, causing an undesirable click or pop [example], at least when using the .m4a format. Most audio players and editors use inperceptible micro-fades to prevent/reduce this artifact. If possible, I think Construct 2 should do the same.
Unless you work with audio a lot, the 'click' hardly feels like the natural result of stopping a sound. It's not what is expected of a Stop action. The click is literally CREATED when you cut off the audio, because the waveform does a straight line back to 0. Why should something be added to the audio that wasn't there originally? And what is the use of this inconsistent sound in games? That's why I think micro-fading the audio is like a higher quality 'stop algorithm' with more natural, useable results. The final thing you hear is the original sound itself, rather than a sharp click. That seems much closer to the behavior we expect.
In any case, if the current method cannot be changed, may I suggest creating a 'Fade Stop' action as an alternative? This would fade the audio down to 0 through a specified number of milliseconds before actually stopping the sample. This I feel would have more uses in games over the current stop method and I believe it would be a worthwhile addition to the official Audio object. What say?