Aureal 3D-Interactive (A3D-I) sound is designed for speaker placement at 
30-degree angles between the centerline of the listener and the speakers.  

The A3D-I effect can be heard on headphones as well.  

Note: The A3D-I effect requires an Intel(r) microprocessor with MMX(tm)
      technology, running at at least 75 MHz (200 MHz or faster for full A3D 
      functionality). 

To select between speaker output and headphone output: 

1. Click Start -> Settings -> Control Panel. 
2. Double-click the "TBS Montego Audio" icon. 
3. Select Speakers or Headphones from the A3D Output Mode pulldown menu. 
   Note: Levels for MIDI Reverb and Chorus effects can be adjusted by 
     clicking  the "MIDI" tab.  A3D-I demos can be run by clicking the 
     "A3D Demos" tab.
4. Click [CLOSE].