What Is An Audio Interface And What Does It Do?

What is an audio interface?

In brief, it’s a piece of hardware that helps improve the sound capabilities of your computer.

It expands the quality and types of sounds, and many audio interfaces even connect to microphones, musical instruments, and other electronic devices that put out sound.

Audio interfaces also allow you to greatly improve the sound quality of your computer. Each time you listen through studio monitors and headphones, or record audio, the interface reproduces even more accurate representations of the sounds you’re recording.

They’re essential when creating any sort of computer-based audio production. Used for making podcasts or recording music, in the post-production of videos, and for voice-overs, an audio interface is a versatile and important tool for anyone involved in video or sound production.

But do you need an audio interface?

Read further.

How Does An Audio Interface Work?


Connecting microphones, guitars, and keyboards, along with other audio devices, is what an audio interface does. But how does it actually work?

Basically, the audio interface upgrades sound output coming into or out of your computer. Now, soundcards also achieve this to some extent, but they’re not intended for higher resolution sounds, and especially for music production or DJs.

Sure, a computer can process sound well enough and generate any noise imaginably, but when it comes to guitars, microphones, or even speakers a computer leaves a lot to be desired. And the same goes for hand-held devices like tablets or laptops.

An Audio Interface Bridges The Gap Between Computer And Studio

The first thing you’ll note is the multiple connections for microphones and an external source – the phantom power – for condenser microphones. Usually, they’ll have high impedance inputs necessary for guitars and other electrical instruments.

They’ll also have a number of line-level inputs too, to record mixer outputs, synthesizers, and other devices. And there’s still space for other recording hardware. It replaces your laptop’s or tablet’s microphone as well, with a professionally connected multi-channel recording interface.

With that, you can plug in, tune in, and make music. On your own, with a band, or even (with the correct hardware) with a full live orchestra.

Along with all those inputs, an audio interface also provides outputs, allowing you to route these through sound processors and external hardware.

It can take individual tracks from your computer or device and mix them through an external mixer. There’s even a headphone output or two, usually with its own level control.

The number of inputs and outputs varies. The ones with fewer inputs are great for portability, but you can get some with over a hundred channels.

Plugging things into and out of a computer wears it out, but audio interfaces are made for just that. Only one cable connects it to your computer. Depending on what you’re planning to do, you may just require two inputs, one for your microphone and one for your guitar.

Digital Interface vs PC Soundcard

Quality counts in music, and video productions for that matter. The more features you require and the more internal components it has, the higher the cost.

The soundcard and other hardware in your computer costs next to nothing, and if you try to record on it, you’ll soon understand why you need an audio interface.

You see, it’s the converters in the interface that record your sound that accounts for the extra cost. Essentially, they’re recording the sound in a digital format. Whatever you’re trying to record, it will sound better with a digital interface than your PC.

The digital interface gives you wider, more dynamic ranges along with the tone you get from professional recordings. Don’t pay attention to your computer’s specs. Its high audio rating of 192kHz will make watching HD movies nominally more entertaining, but it doesn’t translate into clean recordings.

Audio interfaces commonly come in 24 bit and up to 96 kHz. Any sound engineer will tell you, though, that 24 bit and 48kHz is acceptable.

That goes the same for playback. High-quality outputs are essential if you want the best sound. To properly analyze your sound, mix music, work on the intricacies of depth and dynamics, you’ll need something more than a pair of earbuds.

The audio interface gives you professional quality, either through the speakers or through the headphone outputs. Plus you get a proper volume knob rather than having to fool around with a mouse.

Audio interfaces also give you the ability to record, playback, and monitor in real-time. Your computer’s CPU takes a bit of time to process audio, and so if you’re using it directly, there’s a certain amount of delay.

With onboard computer sound, you can hear the delay. It’s very noticeable. With an audio interface that delay becomes unnoticeable, under ten milliseconds. That, by the way, is one hundredth of a second. Much quicker than the blink of an eye.

Yet there can still be delays when using the interface, if you’re monitoring the sound through your computer while recording. When doing large projects, your CPU can get taxed, causing delays.

You can prevent this by switching to “direct monitoring”, common in many audio interfaces, which allows the audio to route back directly, bypassing the computer and preventing noticeable delays.

There are a lot of other advantages. Audio interfaces have physical knobs that control the sound, much easier than relying on a mouse and keyboard functions. Many interfaces also have different speaker outputs that compare mixes, LED monitoring lights, all of which help you record professionally.

Additionally, audio interfaces work at preparing the sound coming into your computer. It ensures that whatever sound you’re recording, it’s high quality.

The Different Types Of Audio Interfaces

Before choosing an audio interface, it’s best to understand what’s out there. And then look at what you want to do with it. For bands, you’ll want enough inputs for all the instruments, vocals, and several microphones just for drums.

Looking at versatility for studio productions, high-end audio interfaces with multiple inputs will be more useful. But if you’re just writing music solo, or with a partner, two inputs will do.

USB Audio Interface

USB ports are ubiquitous, making audio interfaces that use them easy to use with modern devices as well as PCs made in the 1990s. Most laptops or desktops have multiple USB ports.

Additionally, they’re powered by whatever computer you’re using through the USB port, so they don’t require an external power source or power adapter.

So they’re great if you’re wanting to record from home or record a band’s live show, because you don’t need to find a power outlet.

They’re also the most affordable option, so they are the perfect audio interface for neophytes. Not to mention they’re the easiest to set up. A USB audio interface gives you a good bang for your bucks.

FireWire Audio Interface

While USB remains a staple in the tech world, many other alternatives have popped up over time. One of those substitutes being the Firewire, which was introduced in the late 90s.

Firewire audio interfaces have been used over the years due to their high bandwidths with increased performance and stability compared to their USB counterparts.

These devices have a smoother transfer rate compared to other variations. Another reason for the success of the Firewire devices is that multiple devices of the same family can interconnect for additional inputs and outputs.

However, Firewire Audio Interfaces are more limited to professionals with studios since many budget PCs do not support the Firewire cables. If you plan to use this interface, you might have to install a Firewire card before operating it.

  • Supports higher bandwidths than USB 2.
  • Increased performance and stability.
  • Allows streaming data in both directions simultaneously.
  • Can connect multiple FireWire devices for additional inputs and outputs.
  • No built-in on computers, unlike USB.
  • Compatibility issues.

Thunderbolt Audio Interface

There are more audio interfaces on the market now than ever before. They come with multiple connectivity options-one of the most popular being thunderbolt!

Thunderbolt is relatively the best type of audio interface standard when you compare the cost versus performance.

These audio interfaces offer a super-fast 10Gbps connection ensuring a faster data transfer rate compared to the USB and Firewire counterparts. Their performance is like eight times that of a USB Audio Interface.

Many Thunderbolt Audio Interfaces also come with dedicated DSP processing, which ensures that they will not put any load on your computer’s CPU.

This variation offers very low latency performance for the recording and reproduction of audio. Thunderbolt also allows the user to connect various devices like hard drives without compromising speed and performance.

Thunderbolt Audio interfaces are the fastest in the market, making them extremely popular among professionals worldwide.

MIDI Audio Interface

MIDI stands for “Musical Instrument Digital Interface”. Other audio interfaces usually feature MIDI connections and act as a center for a MIDI studio. This feature enables you to control and record MIDI sound modules through your DAW.

Many beginner-level home studio producers focus more on audio features when selecting their preferred audio interface. However, it is worth understanding their MIDI features as well.

Modern keyboard controllers and MIDI controllers have a direct USB connection. This feature means that you may not require MIDI ports in any case.

Nevertheless, if you have more than a couple of MIDI devices to connect, acquiring a dedicated MIDI interface should be at the top of your shopping checklist.

PCIE Audio Interface

This interface is an internal card-based computer connection platform. This feature means that you cannot use these card-based interfaces with laptops.

In recent years, many users have grown to appreciate the ability to work on the move, and the interface market reflects this.

If you are in a situation where more bandwidth is needed, PCle is still the king when it comes to data transfer rates.

This device offers some of the lowest latencies currently available. PCle Audio Interfaces feature in some of the specialist broadcast industry cards for the same reason.

By installing your audio interface into your computer’s CPU, you have the advantage of bypassing some data conversion processes that cause latency and limit bandwidth.

Many of the PCle audio interface’s designs are to manage high track counts and the almost instantaneous speeds required for professional studios. This reason explains why they are pricier compared to the USB and Firewire interfaces.

However, there are affordable PCle devices that allow even entry-level users to take advantage of this format. If you possess any of these interfaces or you plan to update your desktop machine, consider buying one that has a PCle slot available.

Should You Get An Audio Interface?

Now that you know what an audio interface is, should you get one?

Anyone can make a basic recording with a modern computer, laptop, or tablet. They all come with built-in sound cards, after all.

You can even improve sound quality to a certain extent by using a better microphone. But if you want to make a truly professional recording, you’ll need an audio interface.

Before we get to the answer to that ultimate question, let’s look at why you need an audio interface. What are your sonic plans?

For singers or singer-songwriters, you actually don’t need something too complex. One input should suffice, though for more versatility you still may wish to get an interface with two inputs.

For bands or someone wanting to score a film, you’ll need a more complex audio interface. To record your songs or track counts you’ll need something with at least eight inputs.

Film scorers especially will need something to help them compose or mix in surround sound, as that’s what you get in the movies.

For DJs or music producers you’ll need at least four inputs, with two stereo-ready. That way you can route sound through the main speakers while having a separate track playing on the stereo for monitoring purposes.

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And back to that question…

Should you get an audio interface? The answer to the question is simple.

If you don’t want your band, song or mix to sound professional, don’t buy an audio interface. If you want to advance beyond amateur sound and make music like a professional, the answer is a resounding yes.

Juan Stansbury
Juan Stansbury

I'm Juan Stansbury, author and owner of Homerecordio – your ultimate destination for everything about homerecording. With hands-on experience, courses, workshops, and industry research, I offer tips on selecting the best equipment, and mixing and mastering your recordings to achieve professional-quality results at home. Join me on this journey to explore the world of homerecording and music production.

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