How To Choose an Audio Interface

Knowing how to choose an audio interface can be a challenge. There are plenty of things to keep in mind, including budget, features, specifications and, perhaps most importantly, the application. Whether you're recording yourself, a large band, a singer-songwriter, or a string ensemble, Musician's Friend has an audio interface to fit your needs.

Why do I need an audio interface?
Figuring out what kind of audio interface I need
What inputs and outputs (I/O) do I need?
What kind of computer/device connectivity do I need?
What level of sound quality do I need?
We’re here to help

Why do I need an audio interface?

The first question we usually encounter from customers new to computer-based recording is, “Why exactly do I need an audio interface?”

Good question. Your computer already has a built-in sound card. Why not use that? After all, it’s an interface of sorts, isn’t it?

Well, yes, the sound card is an audio interface, but for doing any sort of serious audio work, it leaves a lot to be desired. Consumer-grade sound and limited connectivity severely limit its usefulness when it comes to recording and mixing your music.

Most standard computer sound cards only offer a consumer-grade stereo line level input for connecting audio players and similar gear. For outputs it will likely have a stereo headphone and/or speaker output. And that’s it.

Even if your recording plans are modest—just recording your voice and electric guitar for example—the sound card lacks the appropriate connections. In order to record, you’re going to need an XLR input for your mic and a high-Z phone plug input for your guitar. You’ll also need quality outputs that will allow you to monitor your recording and sound editing using speakers and/or headphones. The output needs to allow you to play back your recordings without the jitter, noise, and latency common with standard computer sound cards.

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Figuring out what kind of audio interface you need

If you’ve browsed the huge selection of audio interfaces at Musician’s Friend you may have felt a little overwhelmed by all the options and terminology. Not to worry—that’s normal and that’s where this buying guide comes in.

Though the range of interfaces is huge, there are just a few key considerations that will help you hone in on an interface that makes sense for your recording needs, music, and budget.

They are:

What inputs and outputs (I/O) do I need?
What kind of computer/device connectivity do I need?
What level of sound quality do I need?
What’s my budget?

On the Musician’s Friend site we make the process of sorting through these requirements easy. Once you’re on the page with the entire audio interface collection, you can filter the results using these criteria (among others):

Price
Number of analog inputs
Connection types
Digital I/O
Computer platform

We’ll address each of these considerations below.

What inputs and outputs (I/O) do I need?

This is one of the most important considerations when shopping for an audio interface. There are a wide variety of different options available. At the basic level, you’ll find simple two-channel desktop interfaces that can record just a pair of mono signals or a single stereo signal at once. At the other end of the scale, there are larger interface systems that can handle dozens—even hundreds—of channels and many inputs simultaneously. What you need comes down to what you plan to record now and in the future.

For singer-songwriters who want to capture their voice and acoustic guitar using microphones, a pair of balanced mic inputs may be all that’s needed. If either of the mics is a condenser type you’ll need an input with phantom power to energize it. However, also consider that you may want to record your acoustic guitar in stereo at some point while simultaneously singing. In this case, two inputs would be insufficient, and a four input interface would be required.

If you’re going to be playing an electric bass, guitar, or electronic keyboard that you want to connect directly to your recording setup, you’ll need an instrument-level input, often referred to as a “high-Z input.”

The super-portable Focusrite Scarlett Gen 3 audio interfaces are available in a number of different configurations.

To connect external gear like drum machines, samplers, and external sound processors such as multi-effects units, you’ll need line level inputs and outputs. Many studio monitors and headphone amps that provide a separate headphone mix to performers also require line level I/O.

Some of your external devices may require digital connections. These include S/PDIF and ADAT connectors which will allow you to connect multi-channel mic preamps to increase the amount of simultaneously available mic preamps in your system (allowing you to record more sources at once), or while freeing up your analog inputs for other gear. An interface with two or four onboard mic preamps and an ADAT input can be expanded to a ten or twelve input unit later by adding an ADAT-equipped external multichannel mic preamp, making this an important feature to look for if you think you may need to expand your system later.

It’s a good idea to make a list of all the instruments and gear you plan to connect using your interface. If you’re unsure about what connections they need, consult your user’s guide or the manufacturer’s website. Then add up the number of connections needed by the gear you want to use simultaneously or leave permanently connected to your interface to arrive at an ideal I/O configuration. It’s also a good idea, budget permitting, to buy more I/O than you initially need since you’ll likely want to create more complex recordings as your skills and gear inventory grow.

Lastly, you’ll want to be sure the interface you choose will play nice with your computer. Though most interfaces work with both Macs and PCs, there are a few that have specific Mac- or PC-compatibility only. Remember to filter your options using the appropriate computer platform checkbox when shopping on Musician’s Friend.

What kind of computer/device connectivity do I need?

With the explosion in recording using computers and iOS devices such as smartphones and tablets, many interfaces are now designed to work seamlessly with them as well as the software and apps that these devices run. Here are the most common connection types:

USB: You’ll find USB 2.0 and 3.0 ports on almost all newer computers, both Macs and PCs. Many of the interfaces designed to work with USB draw their power from the computer or other host device making them ideal for for mobile recording rigs. Most iOS-enabled devices connect to the audio interface using USB.

FireWire: Found primarily on Mac computers and interfaces intended for use with Apple gear, it provides consistent, high-speed data transfer that makes it well suited to multi-channel recording. PC owners can also use Firewire by installing an expansion card in their computer. Newer Apple laptop and desktops are equipped with speedy Thunderbolt ports—see the next entry.

Thunderbolt: This high-bandwidth Intel technology is currently installed on the newest Mac computers. It can also be used on PCs equipped with Thunderbolt option cards. It offers excellent data transfer rates and very low latency performance for the most demanding computer-based recording.

PCIe (PCI Express): This is an internal card-based computer connection platform that’s primarily found in desktop computers. Since these cards are plugged directly into the computer motherboard, they require an available PCIe slot for installation, which some computers may lack. The PCIe connection provides high data bandwidth and low latency, allowing audio interfaces that use it the ability to handle many simultaneous inputs and outputs.

Take a closer look at Universal Audio's Apollo X audio interfaces.

What level of sound quality do I need?

As with most things, you get what you pay for with audio interfaces. Those with the highest quality components, including digital converters and mic preamps, carry price tags that reflect that quality. That said, for all but the most demanding pro-level recording and mixing work, there are some very worthy models available at lower prices. Remember, when shopping online at Musician’s Friend that you can specify your budget in order to find something that works with your wallet.

Here are the key factors and specs that influence overall audio quality:

Bit depth: Digital recording converts your analog audio into bits and bytes. Without getting too technical, the greater the number of bits the higher the level of fidelity as compared to the original signal. Fidelity is largely a matter of how well the digital bitstream can capture the music’s dynamics while eliminating noise. In other words, how faithful the recording is to the original sound.

The audio CD uses a 16-bit standard that delivers a dynamic range of 96dB. Unfortunately the noise floor in digital recording is fairly high, so recording at 16 bits means that some noise will be evident in your music during quieter passages.

24-bit recording, the pro-audio standard today, delivers 144dB of dynamic range, eliminating almost all noise and providing plenty of headroom for very dynamic performances. If you can afford an interface with 24-bit processing you’ll find it will produce smoother, more professional sounding results.

Sample rate: Think of sample rates as the digital snapshots your audio gear captures from moment to moment. CDs use a 44.1kHz sample rate—each second your digital recording system takes 44,100 pictures of the incoming audio signal. This theoretically means that your system can can capture frequencies up to 22.05kHz—well above the range of human hearing.

But it’s not that simple. Again, without getting too technical, there’s evidence that higher sampling rates capture information that contributes to overall fidelity and more satisfying sound. As a result, many studio pros work at 48kHz, 96kHz, or even 192kHz sampling rates.

Deciding what level of fidelity you need comes down to thinking about what you plan to do with your music. If you’re working on a demo to share with friends or fellow band members, 16-bit/44.1/kHz processing should be adequate. But for commercial releases, soundtrack work, and and other pro-level projects, 24-bit/96kHz processing is recommended to help give your sound a professional sheen.

Converter quality: Analog to digital (A/D), and digital to analog (D/A) converters are the devices that convert the incoming analog audio signals into digital data, and the digital data from the computer back into analog audio output signals. Just as critical as bit rates and sampling depth is the quality and accuracy of the converters in your interface. They are where the sonic rubber meets the road. As noted before, bigger price tags generally equate with better quality converters.

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