What is an audio interface, and do you need it?

apollo twin universal audio interface

If you have started to become more serious with music production you have probably stumbled upon the audio interface. 

But what is an audio interface?

An audio interface is a professional sound card that typically connects to a PC via USB or Thunderbolt. It has inputs for connecting guitars and microphones, so you can record live music on your PC.

Let’s look at how audio interfaces work, what they do, and if you really need a dedicated audio interface for your home studio.

What does an audio interface do?

The audio interface converts acoustic signals into digital signals so you can record real guitars, pianos, voices, and other instruments on your computer. 

The benefits of using audio interfaces are:

  • They help you achieve a high-quality result in your recordings
  • As well as handling demanding audio processing and sampling latency
  • And they offer a wide range of input and connectivity options for your instruments, microphones, and computer

To make this easy for you, these are the most common devices you can connect to an audio interface:

  • Guitar (both acoustic and electric guitars)
  • Microphones
  • MIDI Controllers/Keyboards
  • Headphone output
  • Studio Monitors

Why do I need an audio interface?

Put simply, with a good audio interface, you will get high-quality sound and multiple connectors. 

So, if you are planning to record an album or just want your tracks to sound as professional as possible, you will definitely need a solid audio interface.

I have owned a couple of good ones over the years. For the longest time, I used a big, chunky Line6 as my audio interface (the one in the back in the picture below). 

In fact, I still use it, when special circumstances call for it. It has a lot of microphone inputs, you see.

This is why you need an audio interface:

  • Record guitars, drums, voices, and other acoustic instruments on your computer
  • When you experience your built-in sound card is not coping with sample latency 
  • When you need a high-quality, professional sound quality in your recordings
  • When your computer’s built-in sound card doesn’t support ASIO drivers
  • Your computer produces an ongoing static buzzing sound when connecting your studio monitors. Yup, that could happen. My old iMac (late 2009 model) could not handle the direct input of studio monitors.

If you are on the hunt for a quality audio interface and want to know what you should get, you must definitely check out this page, where I recommend my favorite audio interfaces. 

Better sound quality with an audio interface

If you want to record your acoustic guitar, voice, drums, etc, the audio interface gives you the possibility to record acoustic instruments and voices directly into your computer, with great quality. 

And note that I wrote “great quality”. 

Because even though you can also record these things on your computer’s built-in sound card and microphone, this way will never be as good as using an audio interface like for instance the The Focusrite Scarlett .

The Red Scarlett- one of the cheaper audio interfaces out there. But it is a great audio interface!

The performance and sound quality that the built-in sound card is able to produce are simply too poor to be considered a professional solution.

In addition, an audio interface lets you hook up your studio monitors. And even though I mean this is not always necessary, I will come back to why you might need this possibility later in this post.   

Most often, the audio interface connection types are via USB or Thunderbolt. Sometimes, you will also see older audio interfaces that connect via FireWire, but it is not the most common connector anymore.  

The inputs/outputs on most audio interfaces

As you will see in the infographic I have put together above, you can hook up various devices and instruments to your audio interface. 

  • On most audio interfaces, the microphone and guitar inputs are connected in the front (but I’ve also had audio interfaces that had microphone inputs on the backside).
  • Studio Monitors, MIDI Hardware, and other digital hardware are connected in the back.
  • Headphones might be connected both front and back, depending on the developer.

The heart of the studio

An audio interface almost seems like the heart of your studio when you look at the infographic. And there is some truth to that. It controls everything from volume, which signals to send, channels selected, and more.

More connector options and other benefits

An audio interface is actually a professional sound card.

Inside your computer, you have a built-in sound card. The task of the sound card is basically to make your computer able to produce, process, and record sound. 

If you have ever chosen the “Input: Built-In Microphone” option in GarageBand, you have been using the computer’s internal sound card.

The Audio interface is very similar to the internal sound card but it is, of course, external.

Not only that, the audio interface does perform better in most areas, including:

  • Low-Latency
  • Recording
  • Playback
  • Increased connector options


An important difference between the built-in sound card and the audio interface is that the Audio Interface is optimized to have less, to no latency.

This means, that if your computer has a pretty weak sound card, it might be delays between the actual sound and the digital audio signal when you are working in your DAW.

Needless to say, that is not an ideal working situation.

Recording and playback

A standard built-in sound card is mainly intended for playback and casual use, which means it is pretty adept at playing sound from YouTube, Netflix, and Spotify. 

It is not, however, doing a pretty good job at recording.

The sound quality is often either ‘mushy’ or ‘boxy’ like you are talking into a tin can or something. 

And this is obviously not good for an audio professional.

The audio interface, on the other hand, does a great job with recording. As I mentioned earlier, the audio interface is converting acoustic signals into digital ones. 

This is what is called Analog to Digital. 

And this is where a built-in sound card is lacking a bit. The audio interface is much, much more skilled at turning the signal from your guitar into a rich, truthful, and beautifully sounding digital signal that just screams ‘quality’. 

Increased connector options

An audio interface expands your workstation’s input and output connector options. Now, you’ll suddenly have XLR for your microphone, dedicated guitar and microphone connectors, and potentially lots more.

what is an audio interface

This audio interface has two connectors in the front – Guitar, and headphones.

Common Audio Interface Features

We have briefly been touching on this subject already, but here is a greater list of everything you get with an audio interface:

1. A high-quality AD/DA Converter

Converting the analog signal into a digital one, and then converting back to analog so we can hear the sound, is one of the most important tasks featured in the job description of an audio interface. 

So, if you are going to be able to record professional-sounding acoustic music, you need a solid audio interface that converts the analog signal from your acoustic guitar into a digital signal and back again.

The performance of the sound card in your computer is not even comparable to how well the audio interface converts analog into digital and digital to analog.

So, when you combine this with a good microphone, you will get the results you want: excellent, professional sound quality.

2. An increased, improved set of connectors (inputs and outputs)

To work with professional music equipment, you need the right connectors. 

Your computer probably has the standard inputs – a couple of USBs, a jack input, and… maybe not much more than that if you are working on a laptop. 

3. A control center

Thanks to having multiple connectors, the audio interface might end up being the control center in your studio setup.

Or as some people call it: the heart of your studio.

4. ASIO Protocol

This is short for Audio Stream Input/Output and. In short, this protocol provides low latency and high fidelity (high fidelity means that the sound reproduced is of high quality).

What Do all the Technical Terms Mean?

Lastly – here is a list of all technical terms you might expect to run into when considering buying an audio interface.

If you have already been researching audio interfaces online, you have surely seen a lot of technical terms in their product description.

List of common audio interface technical terms

  • Line Out
    This is also referred to as sound out, or audio out and is a jack-input which you can connect headphones or speakers.
  • Monitor
    This is where you connect your studio monitors.
  • Latency
    As you now know, this is a description of the delay between the sound and the playback that might occur when sound cards are too weak to process the signals.Most commonly, a built-in sound card is not built for coping well with latency.
    So, look for audio interfaces that have near-zero latency.
  • Drivers
    This is software that you download and install on your audio interface to make the audio interface communicate with the PC. This software will further help improve the latency issues. Software like this is also possible to install on many built-in sound cards. Drivers like Asio4all are free, and became the solution for me in the period I didn’t use an external audio interface.
  • Direct Monitoring
    If you click this button on your audio interface, you will hear the sound coming from the microphone connected directly to your headphones. Without any delay.
  • MIDI (musical instrument digital interface)
    You might see this input on some audio interfaces. However, since most MIDI controllers operate via USB nowadays, a regular USB connector is sufficient.
  • 48V Phantom Power
    There are microphones out there (condenser microphones mostly) that need power in order to work. If you own such a microphone, you need to look for an audio interface that has a switch for phantom power.
  • Sample Rate
    First, the human ear can generally hear frequencies in the range of 20 Hz – 20.000 Hz (20 kHz).
    To create a digital signal the initial sound has to be sampled. The sample rate is how many samples are created per second. Sample rates are around twice the amount of the frequency rate: for example, the standard sample rate of 44.1 kHz makes it possible to record sounds up to a little over 20.000 kHz.
  • Preamps/Pre-Amps
    A microphone has generally a very low signal. To make it suitable to record something, the signal needs to be amplified. That is why good audio interfaces have good preamps.
  • MC/Line
    This is where you connect a microphone. Most often, this input is an XLR input. XLR is much more stable and balanced over long distances than a regular jack cable. In addition, since the signal level of a microphone is quite low, the XLR will make sure that the sound quality is not destroyed when amplified.

Discover my favorite audio interfaces

Whether you are looking for something affordable or really professional, I have the answers for you. Click the button below to see my favorite audio interfaces across multiple budgets.

Thomas Leypoldt

Hey there! My name is Thomas and I have been a film composer for over 10 years, delivering music to feature films, documentaries, video games, and commercials. I share everything I have learned on this website, to hopefully be of help to your own development as a musician.

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