An audio power amplifier, connected to the VB power rail (battery terminal voltage) for power.
The audio power output may vary as the battery discharges.
- 0.5W stereo speaker output, used for the main speakers.
- 33mW stereo headphone output (32 ohms), for the headphones.
- 43mW mono earpiece output, for the earpiece.
- Line-out, unused.