NAudio library question

Hello guys I am using NAudio and I have this class :

Code:

---

public class Music
{
private string fileLocation;
      private IWavePlayer waveout;
      private WaveStream outputStream;
      WaveOutEvent audio;
      public Drum(string file)
      {
          this.fileLocation = file;
          this.waveout = new WaveOut();
          audio = new WaveOutEvent();       
      }
      static WaveStream CreateInputStream(string name)
      {
          WaveChannel32 inputStream;
          if (name.EndsWith(".wav"))
          {
              WaveStream readerStream = new WaveFileReader(name);
              if (readerStream.WaveFormat.Encoding != WaveFormatEncoding.Pcm)
              {
                  readerStream = WaveFormatConversionStream.CreatePcmStream(readerStream);
                  readerStream = new BlockAlignReductionStream(readerStream);
              }

              if (readerStream.WaveFormat.BitsPerSample != 16)
              {
                  var format = new WaveFormat(readerStream.WaveFormat.SampleRate, 16, readerStream.WaveFormat.Channels);
                  readerStream = new WaveFormatConversionStream(format, readerStream);
              }
              inputStream = new WaveChannel32(readerStream);
          }
          else
          {
              throw new InvalidOperationException("Invalid extension");
          }
          return inputStream;
      }
      public void Play()
      {       
          this.outputStream = CreateInputStream(this.fileLocation);       
          audio.Init(outputStream);
          audio.Play();         
      }
}

---

Sometime when I use the Play void I get this error:
AlreadyAllocated calling waveOutOpen. any idea how to resolve it ?
The other thing I notice is that each time I want to play something I need to open the file read the whole stream and save it in WaveStream, but this way I am wasting the resource and the application memory, any idea how to read it once and then just to use it.