The system volume and DVD volumes are set concurrently to avoid audio distortion. The maximum setting of either volume control is the same and is the highest setting that the computer will allow. However, Mac OS 8.6 installs an updated DVD player, which includes an audio preference for line-out audio mode. DVD users should update to Mac OS 8.6 for more control over audio volume.
The line mode audio setting should be enabled when the DVD audio output is being fed to an amplifier or external powered speakers. If you are listening to the DVD audio-using headphones directly connected to the computer, disable line mode for increased volume. To access this setting choose Preferences from the Edit menu, then the Audio Controls tab in the DVD player application.
Here are some additional suggestions:
- Use headphones that completely cover the ears. This will make a pronounceable difference, as it will help to shield out surrounding noise.
- Use noise-canceling headphones. Noise-canceling headphones contain circuitry designed to block out sound external to the headphones by measuring surrounding noise and creating opposing or canceling sound waves.
- Use an in-line amplifier. A pocket-sized, battery-operated equalizer or assisted-hearing device connected between the headphones and the sound output jack on the PowerBook will allow you to turn up the volume further. Some distortion may occur if the volume is amplified past the default levels set by the PowerBook.