The AstoundSound Expander is a software application that processes all audio on your Mac. It takes stereo audio as input and produces a significantly wider stereo image, while preserving center information (e.g. vocals or center staged instruments), in real time. The result is a wider, fuller and richer listening experience that can be heard while playing music, movies or games. Hear it. Believe it.

After installing the software, the AstoundSound Expander automatically starts when you log in to your system. Controlling AstoundSound is simple and intuitive through the AstoundSound Expander preference pane. The preference pane can be accessed through the AstoundSound Expander menu bar icon or through System Preferences.

The stereo expansion slider is the primary control that increases or decreases the amount of stereo expansion. The lowest setting on the slider will bypass expansion processing.

Other controls include:
- Preamp allows input gain adjustment for improved audio levels
- Audio output device selection
- Listening modes optimize AstoundSound for Music, Movies and Games
- Hot Keys providing quick and easy control of AstoundSound Expander

You can hear the AstoundSound effect through your computer's built-in stereo speakers, headphones, or external stereo speakers connected to your computer. Another great way to hear AstoundSound is to connect the line-out (headphone) jack of your computer to an available input on your home stereo receiver.