The Pi-DAC+ takes the digital audio signals (I2S) from the Raspberry Pi and through the onboard Texas Instruments PCM5122 DAC delivers variable output (hardware volume control) analog audio to the Pi-DAC+ Phono connectors. The PI-DAC+ also, via the Texas Instruments TPA6133A headphone amp, supports the direct use of headphones via the Pi-DAC+ 3.5mm audio jack.
The Pi-DAC+ uses GPIO22 to mute/unmute the Pi-AMP+.
You can use GPIO25 to connect an IR sensor and GPIO23/24 for a rotary encoder. Both of these parts are optional, but are broken out on the Pi-DAC+ for convenient access.
Note: pins reserved for the rotary encoder and IR sensor can be used for other purposes if those add-ons have not been fitted and enabled by software.