how to use thread to playback sound simultaneously in two or three external sound sards

<br />
    public partial class PlaybackForm : Form<br />
    {<br />
    IWavePlayer waveOut;<br />
    string fileName = null;<br />
    WaveStream mainOutputStream;<br />
    WaveChannel32 volumeStream;<br />
    int _deviceNum;<br />
    int _deviceNum1;<br />
    Thread t1;<br />
    Thread t2;<br />
    public PlaybackForm(int deviceNum,int deviceNum1)<br />
    {<br />
        InitializeComponent();<br />
        _deviceNum = deviceNum;<br />
        _deviceNum1 = deviceNum1;<br />
    }<br />
    private void buttonPlay_Click(object sender, EventArgs e)<br />
    {<br />
        if (waveOut != null)<br />
        {<br />
            if (waveOut.PlaybackState == PlaybackState.Playing)<br />
            {<br />
              return;<br />
            }<br />
            else if (waveOut.PlaybackState == PlaybackState.Paused)<br />
            {<br />
                waveOut.Play();<br />
                return;<br />
            }<br />
        }<br />
        // we are in a stopped state<br />
        // TODO: only re-initialise if necessary<br />
        if (String.IsNullOrEmpty(fileName))<br />
        {<br />
            toolStripButtonOpenFile_Click(sender, e);<br />
        }<br />
        if (String.IsNullOrEmpty(fileName))<br />
        {<br />
            return;<br />
        }<br />
        try<br />
        {<br />
            CreateWaveOut();<br />
        }<br />
        catch (Exception driverCreateException)<br />
        {<br />
            MessageBox.Show(String.Format("{0}", driverCreateException.Message));<br />
            return;<br />
        }<br />
        mainOutputStream = CreateInputStream(fileName);<br />
        trackBarPosition.Maximum = (int)mainOutputStream.TotalTime.TotalSeconds;<br />
        labelTotalTime.Text = String.Format("{0:00}:{1:00}", (int)mainOutputStream.TotalTime.TotalMinutes,<br />
            mainOutputStream.TotalTime.Seconds);<br />
        trackBarPosition.TickFrequency = trackBarPosition.Maximum / 30;<br />
        try<br />
        {<br />
            waveOut.Init(mainOutputStream);<br />
        }<br />
        catch (Exception initException)<br />
        {<br />
            MessageBox.Show(String.Format("{0}", initException.Message), "Error Initializing Output");<br />
            return;<br />
        }<br />
        // not doing Volume on IWavePlayer any more<br />
        volumeStream.Volume = volumeSlider1.Volume;<br />
        waveOut.Play();<br />
    }<br />

<br />
  private void CreateWaveOut()<br />
    {<br />
        CloseWaveOut();<br />
        int latency = (int)comboBoxLatency.SelectedItem;<br />
        //if (radioButtonWaveOut.Checked)<br />
        {<br />
            //WaveCallbackInfo callbackInfo = checkBoxWaveOutWindow.Checked ?<br />
            WaveCallbackInfo callbackInfo = WaveCallbackInfo.FunctionCallback();<br />
            // WaveCallbackInfo callbackInfo = WaveCallbackInfo.FunctionCallback();<br />
            // WaveCallbackInfo.NewWindow(): WaveCallbackInfo.FunctionCallback();<br />
            WaveOut outputDevice = new WaveOut(callbackInfo);<br />
            outputDevice.DesiredLatency = latency;<br />
            outputDevice.DeviceNumber = _deviceNum;<br />
            waveOut = outputDevice;<br />
        }<br />
    }<br />