Trouble streaming audio from WWW: plays only part of file

I'm trying to figure out how to stream in audio from a website using WWW. I've read through the documentation and an example or two I found online, and I've come up with the code below.

Unfortunately, it seems that no matter what I try, I can't get the file to play correctly. In a nutshell, what I'm doing is:

• Start a download

• Wait for the download to reach X percent complete

• Extract the clip with GetAudioClip, which is supposed to give you a streaming clip

• Add to an Audiosource and play

I'm seeing very strange behaviour, and I'm trying to figure out if it's a bug or if I'm misunderstanding something. The behaviour is inconsistent: if I try to buffer the clip to 25% complete I see one thing, if I try to buffer to 90% I see another thing, and neither is right.

• If I set the buffer low, say 10% or 25% (www.progress < 0.25f), the audio only plays about a half second, pops a couple times, and dies.

• If I set the buffer high, say 55-90%, it only plays the a second of audio in the middle or end (of a 4 second clip).

I'm hosting a random sample clip here that I'm testing against: http://earth-data.org/arribba.wav.

Is there a different way I should be doing this? Any best practices or samples? Or is what I'm seeing a Unity bug?

 private IEnumerator playAudio(string audioFile)
 {
     //set up a 2D audiosource to play the clip
     AudioSource audioSource = gameObject.AddComponent<AudioSource>();
     audioSource.playOnAwake = false;

     WWW download = new WWW(audioFile);

     //wait for the download to build up a buffer
     while (download.progress < 0.55f)
         yield return null;

     //Get a reference to the audio clip - this should allow us to stream it
     AudioClip clip = download.GetAudioClip(false, true);

     //just in case the isReadyToPlay bit hasn't been flipped
     Debug.Log("Set up audiosource.  Clip ready: " + clip.isReadyToPlay);
     while (!clip.isReadyToPlay)
         yield return null;

     audioSource.clip = clip;

     //start playing when the clip is ready
     audioSource.Play();
     Debug.Log("Playing audio: " + audioSource.isPlaying);

     //wait for the audio to finish
     while (audioSource.isPlaying || audioSource.timeSamples < clip.samples)
         yield return null;

     Debug.Log("Finished playing the audio clip.  Cleaning up");
 }