Apple TV/FM Radio System - Manual (Page 86)

The sound controls appear.
3 Click the sound mode you want to use (Mono, SAP,
or Stereo).
The new mode takes effect immediately.
Adjusting speaker balance and tone
To adjust the speaker balance, bass, or treble:
1 Choose Show Controls Window from the Windows menu.
2 Click the sound icon.
3 Drag the appropriate slider to adjust the sound to your
liking.
You can also click anywhere in a slider’s track to move the
slider to that position. The sound adjustments take effect as
you make them, so you can monitor your changes.
Note: You’ll only be able to hear changes in balance if
you’re using external speakers or headphones.
79 Watching TV or Video