What Is An Audio Interface and Do You Need It?

Martin Kristiansen

My name is Martin Kristiansen and I’m the founder and chief editor of HomeStudioIdeas.com. I’ve been playing, recording and producing music for the last 10 years.

Today’s computer-based digital audio workstations (DAW) software and virtual plugins give you more music production power than any studio packed with analog outboard gear. Despite all the functionality the software provides, they rely on a single piece of hardware: the audio interface.

So what is an audio interface, and do you really need one? It’s a very logical question because it’s way too easy to spend your hard-earned cash on things you don’t need when setting up your first home studio.

As we’ll show you in this post, the interface is an essential piece of equipment! Read on to learn more about their functionality!

What Is An Audio Interface?

At its core, an audio interface is an external soundcard with inputs for mics and line-level instruments. Besides inputs, it offers vital connectors you need to plug in your speakers and headphones for listening.

But there is more to it. 

An audio interface acts as the front end of your computer recording system.

Let’s take an example where you connect a microphone and record yourself singing:

First, when you sing into the mic, it converts the physical vibrations of air into an electric signal. This electric signal travels down the connecting cable to your audio interface’s mic input.

Secondly, the signal gets sent to the interface’s A/D-converter (analog-to-digital) and transforms to digital audio data. Why? Because your computer doesn’t understand analog audio. It reads digital language and digital audio, which contains a stream of ones and zeroes.

The digital signal is then sent to your computer’s DAW through either a USB cable or Thunderbolt cable. Your computer hosts your DAW that records the digital signal.

Now, we can’t hear digital signals. For us to be able to hear the recorded audio from the mic in our playback system, the now-digitized audio needs to be converted back to analog. Luckily, the audio interface takes care of that as well. 

The digitized signal is carried out by the interface’s built-in D/A (digital-to-analog converter). The now-analog electrical signal is available at the interface’s line outputs where it gets carried out to either a pair of studio monitors or headphones.    

To sum things up

Audio Interface vs. Sound Card

Technically, audio interfaces and sound cards are the same thing. Both convert the incoming analog signal to digital and vice versa. So what’s the difference?

Let’s say you want to record yourself singing and playing guitar. You’ve found a line-in jack and a microphone jack on your computer. Unfortunately, sound cards only allow you to record one input at a time, meaning you can’t record both simultaneously.

Audio interfaces also have higher quality A/D and D/A converters which allows for much better sound quality. This makes them ideal for music production. 

In addition to this, interfaces offer better mic preamps than sound cards. A preamp boosts the incoming signal to a usable level without adding noise or distortion to the sound. Again, sound cards have preamps, but of much lower quality.

Last but not least, latency. Imagine singing and hearing your voice a second later.

That’s exactly what latency is. The time it takes for the incoming signal into the PC to get processed and sent back to your playback system. That can be a huge issue with built-in sound cards. Although some latency always occurs in audio interfaces as well, it’s not noticeable.

Do I Need An Audio Interface?

If you rely heavily on audio recording, then you need an audio interface. Not only will they allow you to record multiple audio tracks simultaneously. Thanks to premium preamps and converters, an interface also offers an overall better sound quality.

Although your computer has a built-in sound card, producers need an audio interface with dedicated drivers that can handle the heavy signal processing that goes on when you record, edit, and mix your songs. Without an interface, you will experience delays and drops in sound quality.

Besides the perks mentioned above, an interface offers more than consumer-grade inputs like line-in and microphone jacks. Even if most budget audio interfaces only have one or two inputs, they consist of both XLR-inputs and balanced line-ins. Premium interfaces can also include MIDI In and Out, SPDIF, ADAT, and Word Clock.

You could argue that you don’t need an audio interface if you’re only producing tracks with MIDI. Since most MIDI keyboards can be connected via USB, you don’t need MIDI I/O for the most basic setups. Also, no audio is being recorded so mic preamps, A/D/ and D/A converters are out of the equation.

Still, there are some great affordable audio interfaces on the market. At some point, you may want to upgrade and start experimenting with recordings. Besides, there are some great home recording studio packages available if you want a bundle deal.

Which One Should I Choose?

There are many interfaces available and the most basic have USB connectivity. If you have more money to spend and want even more performance you should consider an interface with Thunderbolt or Firewire connectivity.

As an example, Thunderbolt 3 has incredible high speed and low latency. It’s 8x faster than a standard USB 3 connection. Thunderbolt is the new standard on the latest iMac devices, and if you’re on PC you need to check for USB-C ports with the Thunderbolt logo.

If you’re looking to record multiple channels at once, Firewire connectivity is a reliable option. The advantage of Firewire is that it transfers data at a more consistent rate compared to USB. If you’re using a PC you might have to shell out money and install an external Firewire card. 

Still, if you’re just starting out with a basic setup, a USB interface will do just fine. Many interfaces are also designed to run on USB bus power, meaning you don’t need an external power supply.

Another feature to consider is the number of inputs. If you’re looking to record an entire drum kit, you’ll need more than two mic preamps. On the other hand, if you only want to record one source at a time, you only need one input.

There are many great options available but my favorite audio interface is the Focusrite Scarlett 2i2. Why? Its award-winning preamps are outstanding. The Air setting gives your vocals and recordings a brighter, more expansive sound. As the name suggests, it features 2 inputs and 2 outputs.

If you’re looking for an audio interface with more than 4 inputs, I would recommend the M-Audio M-Track 8x4m. It features 4 rear-mounted balanced combi mic/line inputs, 2 front-mounted unbalanced instrument inputs, and 2 rear-mounted balanced line-level inputs.

Other great options includes:

Conclusion

In essence, an audio interface is a piece of hardware that connects your microphones and other outboard gear to your computer. Interfaces also convert the incoming analog signals into a digitized signal that your computer can process.

There are several reasons to use a dedicated audio interface instead of your computer’s built-in soundcard. Compared to sound cards, interfaces have a superior sound quality along with minimal I/O. Sound cards are also equipped with consumer-grade stereo inputs and outputs, making them vulnerable to jitter, electromagnetic, and radio interference.

An audio interface is an essential component for your home studio setup. It allows you to record more instruments and devices, without any noticeable latency (delay between the sound and playback).

To conclude, you should most definitely consider buying one if you want to record high-quality audio.