== Hardware setup ==
The SD card should be connected to the SPI port of the controller. The chip select pin from the card can be connected to any free digital pin, but if pin 4 is used on Arduinos you don't have to adjust the source code. Many shields with SD card support like Ethernet-Shield will work. You need level conversion circuits from 5V to 3.3V for most Arduinos (except those that run natively on 3.3V) - three resistor dividers are enough. Look this at the circuit diagram below how to do it: [[Datei:SD_Card_Connection.png|frame|left|SD card connection with level shifting to standard Arduinos]]
According your mode configuration, one or two pins are used for audio output. This pins can not be changed and are different between different Arduino boards. For ATmega168/328 based plattforms those are pins 9 and 10. For ATmega1280/2560 those are pins 44 and 45. For other plattforms look into the file SimpleSDAudio.h.
Be careful that the audio output pins are digital ports that carry a positive voltage between 0V and 5V. It is not a good idea to have a DC voltage at line-inputs or smaller speakers as there will be a steady current flow. Therefore at least a resistor and/or a capacitor should be connected in series. For a start use at least 100 ohm or a capacitor between 100nF and 100uF. For line inputs use a voltage divider or poti to reduce the voltage.
<gallery widths=300px heights=150px perrow=32>Datei:SD_Card_Connection.png|SD card connection with level shifting to standard Arduinos
Datei:SSDA SimpleConnections.png|Examples for simple 8-bit audio outputs
Datei:SSDA Simple16bit.png|Rising the audio resolution to something near 16-bit