Download an audio file in background without lags.

Hello, I have a problem with loading an audio file from HDD, more precisely while it loads, the game stops until it is fully downloaded even if I use yield's or other coroutine methods. Am I doing something wrong or it has to be done using streaming? (which I once used but want to avoid it this time, too much work and code involved)

Here's the code am using right now:

 @HideInInspector var musicFolderContents : String[];
 @HideInInspector var customPlaylistSwitch : int[];
 private var musicPlaylist : int[];
 private var actualMusicID : int;
 private var externalMusicScan : int;
 private var bufferedAudioclip : AudioClip;
 private var HDDaudioFile : WWW;
 var playNextTrack : boolean;
 var actualAudioTrack : String;
 function MusicPlayer (){
     if (playNextTrack){
         bufferedAudioclip = null;
         // Play music from internal library
         if (musicPlaylist[actualMusicID] < originalMusic.length){
             bufferedAudioclip = originalMusic[musicPlaylist[actualMusicID]];
         } else{ 
         // Play music from external folder
             actualAudioTrack = Path.GetFileNameWithoutExtension("file://"+musicFolderContents[musicPlaylist[actualMusicID]-originalMusic.length]);
             if (Application.isEditor) HDDaudioFile = new WWW ("file://"+musicFolderContents[musicPlaylist[actualMusicID]-originalMusic.length]);
                 else HDDaudioFile = new WWW ("file://"+Application.dataPath+"/Music/"+musicFolderContents[musicPlaylist[actualMusicID]-originalMusic.length]);
             bufferedAudioclip = HDDaudioFile.GetAudioClip(false, false);
         }
         actualMusicID = (actualMusicID + 1) % musicPlaylist.length;
         playNextTrack = false;
     }
     if (bufferedAudioclip != null){
         if (musicPlaylist[actualMusicID] < originalMusic.length){
             audio.clip = bufferedAudioclip;
             audio.Play();
             bufferedAudioclip = null;
         } else{
             if (HDDaudioFile.isDone){
                 if (bufferedAudioclip.isReadyToPlay){
                     audio.clip = bufferedAudioclip;
                     audio.Play();
                     bufferedAudioclip = null;
                 }
             }
         }
     }
 }