STK1000/Audio, internal DAC
From AVRFreaks Wiki
The output from the internal DAC on AVR32 devices that support this are routed to the audio connector on STK1000.
See the selection on jumper settings for an explanation of how to select output to the stereo headphones.
Block diagram
Signals
The output from the internal DAC go through an optional filter. This filter is not normally populated and instead bypassed by a 0 OHM resistor.