How does an Audio Interface work? (Explained for beginners)

By Bob •  Updated: 10/26/21 •  7 min read

If you want to record music onto your computer you will need an audio interface.

An audio interface enables you to connect a microphone or an instrument to your computer and it can also be used for line-level outputs.

Once the external audio is plugged into the interface, the sound will then go through a preamp that boosts it to line level.

This audio is then converted from analog to digital and then sent to the computer.

Once inside the computer it is either stored on your hard drive or passed through to a recording program where it can be edited, affected, mixed, and saved.

An audio interface usually has more than one channel which means that you can record multiple tracks at once without having to use multiple interfaces.

What is an Audio Interface?


An audio interface is hardware that is used for connecting audio gear, such as microphones to computers.

The device works by converting analog signals into digital.

This gives you the ability to record and store your music right on your computer’s hard drive rather than just on tape or disc.

It also allows you to use DSP effects in real-time without taxing your CPU or having to purchase extra software.

Features to consider when buying an audio interface are the number of inputs and outputs, compatibility with your computer platform, I/O types, sidecars, weight, and a number of channels.

You also want to make sure that the device has phantom power for condenser microphones along with preamps which will give you more control over your external sound sources.

Analog RCA jacks are better suited to consumer-level equipment whereas 1/4-inch TRS connectors are better used with professional-level devices.

You should have line inputs on your interface so that it’s compatible with virtual instruments, keyboards, drum machines, turntables, and other stereo mixers.

If you want an inexpensive 2 channel interface you should consider getting one that has mono 1/4-inch TS instead of balanced XLR or unbalanced RCA.

These somewhat cost-effective audio interfaces will give you all the basic functions that you need to start recording with your computer at a reasonable price.

When do you need an Audio Interface?

You might need an audio interface if you are into recording yourself or others, be it for musical purposes or podcasting.

It’s also useful if you want to record live music and play virtual instruments on your computer.

An audio interface is also helpful if you want your computer to communicate with other devices that have line-level outputs like mixers, MIDI instruments, and studio monitors.

There are even USB audio interfaces that you can plug into tablets and smartphones for on-the-go recording.

Types of Audio Interfaces

iPad/USB Interface: This type of interface plugs into either your Apple tablet or an external USB port to get a line-level output from your device.

Computer Interface: These types of interfaces connect with a computer through a high-speed USB, Firewire, or Thunderbolt connection in order to record your music directly to the hard drive.

MIDI Keyboard Controller: These allow you to plug in a MIDI keyboard or controller and turn it into a hybrid synthesizer via software integration.  

It also gives musicians the ability to control DAW functions without having to use their mouse which makes programming and mixing a whole lot easier.

USB Audio/MIDI Interface: This type of interface has both line level and MIDI ins and outs all in one.

Signal to Noise Ratio: The higher the signal to noise ratio is, the clearer your music will sound through the preamps and converters on your audio interface.

Manufacturers such as M-Audio, Presonus, TASCAM, Roland, and Behringer offer good quality interfaces for home recording studios.

How to choose an I/O configuration for your Audio Interface

Choosing the right I/O configuration for your audio interface is really a matter of what type of sound sources and outboard gear you’ll be using.

Here are some guidelines for choosing the best I/O configuration for your home recording studio.

Stereo Ins/Outs: These give you two channels of I/O and are the ideal choice if you plan to record multiple sources.

Quad Ins/Outs: This type of I/O configuration gives you four channels which are great for recording drums, percussion, and synth parts.

8-Channel Configurations: This kind of I/O configuration can handle 8 tracks at a time and is perfect for recording full bands or overdubbing vocals in larger studios.

16+ Channels: If your home studio needs more ins and outs then an interface with 16 or more channels will be the most cost-effective option.

How does an audio interface connect to a computer?

It’s not that difficult to understand how an audio interface connects to a computer.

All you need is the proper cable and your desired output configuration in order for it to work properly.

Simply plug one end of each cable into the corresponding port on the device and the other ends into the appropriate slots on your interface.

Your computer will recognize these signals as sounds coming from your external sound sources which you can record with a DAW or use virtual instruments with a MIDI controller.

Do you really need an audio interface?

Yes, if you want to make decent recordings onto your computer you will need an interface.

Even when you make your own music or create electronic beats.

The major reason is the audio quality required for professional music production.

Most sound cards sold on laptops and desktop computers do not provide this level of excellence.

An audio interface will allow you to record, mix and master your music without sacrificing the sound quality.

How much does an Audio Interface cost?

There are many different types of interfaces with varying price ranges for both home recording studios and professional producers.

Here are some examples of interfaces that cost around $200 or less.

Focusrite Scarlett Solo
ART USBMix4 Four Channel Mixer/USB Audio Interface
M-Audio M-Track Plus
M-Track Plus

If you’re looking for a more advanced interface like one used in large recording studios then prices between $500-$3,000 are the range you should be looking at.

Tascam US-4×4 USB Audio/MIDI Interface with Microphone Preamps and iOS Compatibility
Mackie Onyx Blackjack 2×2 USB Recording Interface
PreSonus AudioBox 96 Audio Interface Full Studio Kit with Studio One Artist Software Pack w/Atom Midi Production Pad Controller w/Mackie CR3-X Pair Studio Monitors & 1/4” Instrument Cables