The Pi-DigiAMP+ is an add-on board that includes a Digital to Analog Converter (DAC) and powerful 35w stereo amplifier. If you want to turn your Raspberry Pi into a working Hi Fi stereo, just add speakers and you're off.
The Pi-DigiAMP+ exposes some of the Pi's pins via a header.
Pin | Name | Name | Pin
--- | --- | --- | ---
1 | GPIO23 (Rotary encoder) | GPIO22 (Mute) | 2
3 | GPIO24 (Rotary encoder) | GPIO25 (IR) | 4
5 | 5v | 3v3 | 6
7 | I2C SCL1 | Ground (0v) | 8
9 | I2C SDA1 | Ground (0v) | 10
These can be used for whatever you like but some are used by some additional software the IQAudIO provide to easily support a rotary encoder for physically controlling volume, a hardware mute switch and IR control.
The official documentation can be found on the [IQAudIO website](http://www.iqaudio.com/downloads/IQaudIO.pdf).