What is an Audio Interface? Explained Clearly

What is an Audio Interface

If you’re new to the world of music production and want to record music at home. You need to find a way to get audio into your computer. How do you do that? Well, firstly you need audio software, this is known as a DAW and you can read all about that in my article What is a DAW? Secondly, you need an audio interface. But what is an audio interface? What is an audio interface used for? Do you need one? And which type do you need?

I’m glad you asked because the answer is not so straightforward. Like most audio gear, there are various options to choose from and some technical jargon to understand. If only there was someone you could depend on to explain it clearly to you. Someone who writes easy to understand explanations and designs clear diagrams… Oh wait, that’s me. Lucky you! I wish I had someone to explain it all to me when I began.

It’s Normal to be Confused

I remember being in the exact boat as you. In fact, when I got my first audio interface (a Digidesign rack 002) I was completely baffled about what all the buttons did, and what the purpose of all of the inputs/outputs were. I approached my flatmate who was studying music to ask for help, but even he was perplexed by some of the technical names written on the interface. That’s why I created this website and my YouTube channel, to help you navigate through this new world.

In this article I’m going to explain exactly what an audio interface is, it’s functions, the different types, and the most complex topic, the inputs and outputs. I can guarantee that after reading this article you will have a clear understanding of audio interfaces, and you can make a purchase without any more confusion. Let’s begin.

Audio Interface Overview

What is an audio interface? Simply put an audio interface is a piece of hardware that allows you to get audio into your computer, tablet or iPad. You can’t plug in a microphone cable (XLR) or an instrument cable (TRS/TS) directly into your computer, so you need an in-between device to do the work for you. Want to read all about audio cables? Check out my article explaining audio cable connector types. You also need an audio interface to get audio out of your computer so it can be heard through headphones or studio monitors (speakers). 

Analog to Digital Conversion
An audio interface converts an analog signal (such as a singer singing into a microphone) to a digital one.
Digital to Analog Conversion
An audio interface also converts a digital signal (such as an audio file) to an analog signal.

Audio Interface Buttons and Controls

Before we go into inputs and outputs, let’s examine some typical controls and functions you would find on an audio interface.

Audio Interface Buttons and Controls

Audio signals coming from an instrument or microphone can often be too low, so we use the gain knobs to turn up their volume. If the the volume it too loud, some audio interfaces have some LEDs or a meter to tell you if the signal is too hot. In that case you should turn the gain knob down.

If your audio signal is still too loud, you can press the PAD button, which reduces the volume by a fixed amount, it’s quite a common feature an audio interface. Microphones require more power than instruments so all audio interfaces have a phantom power button which delivers 48V of power to a microphone. Finally, you have a volume control for your studio speakers and headphones. Simple so far, right? Well, brace yourself but next were going to talk about inputs and outputs which can get a little bit confusing.

Audio Interface Inputs and Ouputs

Inputs allow you to send or get audio into your audio interface. So, the more inputs you have, the more instruments you can record. If you’re a solo musician like an electronic music creator, singer, or guitar player, 1-2 inputs will suit your needs. If you play in, or want to record a small group with a mix of electric/acoustic instruments, 4-8 may get you by. However, if you will be recording a full band at once, you’re going to need 20+, bearing in mind it’s common practice to use at least 8 microphones on a drum kit; it depends on your needs. Let’s break down the basic types first. MIDI


  • Mic Input – Allows you to connect and record a microphone directly into your audio interface.
  • Instrument Input – For connecting and recording low signal (known as instrument level) instruments like a guitar or bass.
  • Line Inputs – Enables you to record hot signal (known as line level) instruments like a synthesiser or electric piano.
  • MIDI Input – Gives you the option to connect and record a MIDI device, such as a MIDI controller, or MIDI keyboard. However, note that most MIDI keyboards can be connected to your computer directly by USB these days.

Audio Interface Inputs and Outputs


Outputs allow you to send audio out of your audio interface to some headphones or studio monitors so you can listen to your music. You may also want to send your audio to some external hardware such as an effects unit, compressor, limiter, EQ unit, and so on.

  • Headphone Output – Simple enough, lets you plug in and send audio to your headphones.
  • Monitor Output – Allows you to connect and send audio to your monitors (studio speakers).
  • Line Output – Lets you connect and send audio to your studio monitors, or external hardware.
  • MIDI Output – Enables you to send MIDI data from your DAW to a MIDI device, for example to a sequencer or synthesiser.

Additional Inputs and Outputs

On more expensive audio interfaces, you can find some additional inputs and outputs that give you more connectivity options. These inputs and outputs simply allow you to receive or send audio to, and from other types of external hardware.

  • SPDIF – Can send or receive two channels of audio. You could use it to connect CD or DVD players, game consoles, effect units, and some synthesisers also use SPDIF.
  • Optical (ADAT) – Can send or receive eight channels of audio, so optical is more versatile than SPDIF. You could use it connect a mixer, PA system, or you could connect another audio interface to your original one, giving you more inputs and outputs.
  • World Clock – When you connect one or more audio interface together, they can become out of sync which cases clipping, noise, and distortion. We use the world clock to make one ensure that they are synchronised correctly, working in perfect harmony together. Now everybody is happy.

Phew! I’m glad we got through all of that… I know it can be a lot to take in when you’re just beginning. I remember when I started out, I bought a very old Digi 002 rack from eBay. When it arrived and I had absolutely no idea about what all of the inputs/outputs mean. So, don’t feel bad if it’s a lot of information to take in.

Audio Interface Connection Types

Audio interfaces can be connected to your computer via various cables types, which process data at different speeds. There are four common types used for audio interfaces.

Audio Interface Connection Types•  USB – Offers the slowest transfer data rate, typically found on budget interfaces for home studio use. 

•  Firewire – Faster than USB, found on more expensive home studio devices. Nowadays, these are becoming less popular, due to Thunderbolt.

•  Thunderbolt – Much faster than both USB and Firewire, becoming more popular on semi-pro interfaces.

•  PCIE – Extremely fast data-transfer, used for professional interfaces when high processing power is required.

Despite USB being the slowest, it’s more than fast enough for the majority of home studios. Regardless of which connection type you choose, make sure your computer is compatible.


Mac Logo and Windows LogoWith regards to compatibility, most audio interfaces are compatible with Mac and Windows, and most, if not all are compatible with every DAW available. So, you don’t have to worry there, although it’s good to always double check, just in case.

Something else you may look for, is if the audio interfaces’ DAW can be used with an iPad, iPhone, or tablet. Some offer that ability, giving you the option to connect multiple devices at once, making your workflow much faster.

Do audio interfaces include any software?

Focusrite Scarlett Series Software BundleIf you’re just starting out in the world of recording music, lucky you, you’ve come at a great time. It’s never been easier to create, record, and produce music at home. As audio technology has developed, products have become more advanced and budget friendly. As soon as a company ups their game and offers more, others have to compete, or at least match what’s on offer.

A lot of audio interfaces today come with software bundles, this can include DAWs, plug-ins such as EQs, compressors, limiters, reverbs, modulation effects, amps, virtual instruments, and more. This puts you in a brilliant position to get recording right away, and producing professional sounding music, providing you make good use of the resources available. 

Audio Interface Form Factors

This geeky jargon simply refers to the size and shape of the interface, there are two types to consider.

Desktop Audio Interface and Rackmount Audio Interface•  Desktop Interfaces – Smaller and able to sit on your desk, next to your computer.

•  Rackmount Interfaces – Larger and mounted on a rack unit. However, you don’t have to mount them on anything. You can still just place them on top of a desk. That’s exactly what I do with mine, but shhhh don’t tell anyone…

If you’re just starting out, or need something minimal, then I’d suggest going for a desktop interface because they’re simple and easy to use.

If you want something more advanced, versatile, and flexible with regards to signal routing and inputs/outputs, then consider a rack mounted interface.

How much does an audio interface cost?

The biggest difference between low priced audio interfaces, compared to high priced ones, is how many inputs/outputs and connectivity options are available, plus the recording quality. Expensive audio interfaces have better preamps and components, resulting in better audio quality.

Man in Home Recording StudioFor beginners, home studio owners and budget studios, a moderately priced audio interface will serve you perfectly well. If you’re running a professional studio, recording full bands, charging clients high sums of money, then you should indeed invest in an expensive higher quality audio interface, or even better, a mixing desk.

It’s important to remember that gear isn’t everything! Producing great music starts with a great performance. Recording equipment has come a looooong way in the past few decades. Budget audio equipment is more than capable of producing professional sounding music, especially with the tonne of plug-ins that are available to enhance your mixes.

What audio interface should you buy?

I hope that after reading this article you now have a clear idea about what an audio interface is, what an audio interface is for, what it does, and how it works. If you’re a podcaster, live streamer, musician, or music producer you need an audio interface to record professional sounding audio. Trying to choose the right one for you is not easy, as there are so many options to pick from. Ultimately, one of the most important factors for you is likely to be price.

To help you out I’ve written an article listing the best audio interfaces from low to high price, detailing what software is included, and the inputs and outputs available for each. Don’t overthink too much which one to purchase. They all serve the same basic function of getting audio in your computer. As long as you know how many inputs and outputs you need, then any from my list will serve you well, as they all have a renowned reputation for longevity, reliability, and quality.

New to audio production and what to know what other equipment you need? Check out my article here.

I hope you found this guide helpful. If you have any comments, or questions, feel free to write them below.