C#にてDirectXのAudioVideoPlaybackを利用した同時再生。

AudioVideoPlayback.Audio.cs

using Microsoft.DirectX.AudioVideoPlayback;

private void button1_Click(object sender, EventArgs e) {
 Audio  audio1 = new Audio(@"C:\Windows\Media\tada.wav");
 audio1.Play();
}

private void button2_Click(object sender, EventArgs e) {
 Audio  audio2 = new Audio(@"C:\Windows\Media\chimes.wav");
 audio2.Play();
}