void createAUGraph ()
{
        AUGraphError result = 0;
        int samplerNode, ioNode;

        var sampler = new AudioComponentDescription () {
                ComponentManufacturer = AudioComponentManufacturerType.Apple,
		ComponentType = AudioComponentType.MusicDevice,
		ComponentSubType = (int)AudioTypeMusicDevice.Sampler;
        };

        processingGraph = new AUGraph ();
        samplerNode = processingGraph.AddNode (sampler);

	var output = new AudioComponentDescription () {
                ComponentManufacturer = AudioComponentManufacturerType.Apple,
		ComponentType = AudioComponentType.Output;
		ComponentSubType = (int)AudioTypeOutput.Remote;
	};
        ioNode = processingGraph.AddNode (output);

        processingGraph.Open ();

        result = processingGraph.ConnnectNodeInput (samplerNode, 0, ioNode, 0);
        if (result != AUGraphError.OK)
                throw new Exception ("Unable to open the audio processing graph.  Error code: " + result);
        samplerUnit = processingGraph.GetNodeInfo (samplerNode);
        ioUnit = processingGraph.GetNodeInfo (ioNode);
}