The computer's sound card is a part that offers aural input and output features. Most sound devices have at least one audio line output port and one analog line input. Most headphones use 3.5 mm minijack connections, which are the standard measurement for sockets. Some sound devices also allow digital audio input and output, either via an optical audio interface, like a Toslink adapter, or through a normal TRS (tip-ring-sleeve) connection.

Despite the fact that there are many different kinds of sound devices, any kind that generates an analog output needs to have a digital-to-analog adapter (DAC). By doing this, the digital output stream is changed to an analog one that can be broadcast through most audio systems. Music devices with analog input need an analog-to-digital translator as well (ADC). In order for the computer to handle the inbound analog data, this digitizes it.

Some computers' sound cards are built into the processor, but other computers might use a separate card that slots into a PCI port. You can install a new sound device if you want to give your computer more audio features, like extra input or output channels. Professional sound devices frequently have more inputs and outputs and can handle greater recording rates (such as 192 kHz instead of 44.1 kHz). Additionally, some devices might use 1/4 in. connections rather than 3.5 mm, which can handle the majority of instrument outputs.

While expert sound devices can expand your computer's audio powers, expansion boxes are a common alternative for multi-channel recording. This is an exterior unit that usually has numerous audio ports and an integrated sound device. For instance, an expansion unit might be able to accommodate 16 audio channels, which would not work on a single card. Although some breakout boxes link to a sound device specially made to interact with the box, most breakout boxes connect to a Firewire or USB interface.