How we test audio interfaces

Audio interfaces have become ubiquitous with the creative musician, a critical component of the 21st century’s evolution in how music is made, and distributed, alongside the massive growth of music streaming. Nearly every musician can afford an interface nowadays, making it an essential part of the music-making lexicon. Nowadays, entire albums can now be created on a simple 2-channel audio interface .

Here at MusicRadar , our writing team has tested a huge variety and hundreds of audio interfaces over the last couple of decades, which act as a base for product selection in our buying guides. We use a rigorous process when conducting our reviews, carefully testing each product to ensure an accurate overview for the consumer as well as a direct comparison with others in the market.

How we select products

All of our recommendations are made purely based on the product’s merit - nobody tells us what to say in a review, or what we should or shouldn’t review. All the content that goes into our tests is the expert view of the writer, who will have experience in the field and will have reviewed many other products in that category. We never take money for a review, operating independently of every manufacturer, and we’re never afraid to point out the flaws in a product.

We’re usually in direct contact with manufacturers who will send us a sample product for review, however, if we’re unable to source it this way, then we will buy it with our own money. When selecting products we rely on our own experience, discussions with other editorial staff, as well as experiences of others in our local music scene to determine which are the most popular or top-performing products that are worth reviewing.

We try to test every single product that we recommend personally, but of course, this isn’t always possible. You will find in most of our buying guides that we have tested a large portion of the products, which allows us to provide a useful recommendation in any instances where we haven't been able to get hands-on.

How we test

All of the audio interfaces we test must meet a certain barrier when it comes to quality, and we are always careful to test products thoroughly. Here are the aspects of an audio interface we'll examine during testing:

Features

Our first step is to outline the features of the unit in question. We’ll look at connectivity, for example, the amount of ins and outs, alongside additional options like ADAT and MIDI, and more common components like headphone sockets and USB connections. Understanding the features of an audio interface tells us a lot about where it sits in the market, who its potential users will be, and where we might want to place it in our own buying guides.

Features can also encompass simple things like the number of controls it has, whether or not it has phantom power, or if it comes with a USB or Thunderbolt cable in the box. What we glean from the features of a product fuels the rest of the review process, as it’ll need to meet different criteria depending on whether it’s designed for beginners recording at home or those working in professional studios.

We’ll also look to compare the features list to other similarly priced audio interfaces. We’re looking to see how it holds up to others, whether that’s a more established name or someone new to the industry. We’ll compare the amount and quality of preamps, gain range on the inputs and outputs, as well as the sample and bit rates. This will all be done through the lens of the price, as there’s not much point comparing a $2,000 interface with a $200 one.

Build quality

We like to get hands-on with our audio interfaces, taking them straight out of the box and giving them a good in-depth look and feel. We’re judging whether it feels plasticky or cheap overall, as well as checking for any visual defects that might hint at poor craftsmanship. We’ll see if it has rubber feet and how heavy it is, as light interfaces with heavy cables can result in them getting pulled off the desk.

We’ll also check the feel of the knobs, as we want to know if they’re nice and grippy, as well as not being too stiff or too loose, and do the same for any buttons. We want to feel that the unit is going to last, and not that it’s going to break the moment you’re a little too overzealous turning the volume up. It’s also good to know that a unit is durable enough for mobile recording sessions, as recording drums or loud guitars at home often isn’t an option.

Installation

When we test audio interfaces we’re aiming to use them exactly as any musician would, so our next step is to install the interface on our computer or laptop. To ensure balance, we’re obligated to test the interface’s installation process on both WIndows and Mac OS as well. We’re looking to see how easy the overall process is, whether there are any potential pitfalls on each platform, or whether you need to do some further investigation to get your interface working as it should.

Most audio interfaces on Windows require a driver to be installed, so it’s important to include this in our review. Not everyone is ultra tech-savvy, so where we can offer suggestions for third-party software or offer further advice on installation, we will. Typically Mac installations will be a lot easier, but they’re not without their pitfalls either.

Many interfaces come with a dedicated software app, so we’ll install this too, noting any differences in the process between Windows and Mac. We’ll then examine the various options available in the software, and how useful they’ll be to the musician or creative using them. Good software should allow you to change the buffer and sample rates at the very least, and with most modern apps we’d expect there would be more features, like adjusting input volume and loopback functionality.

Audio interfaces also tend to come with additional software such as plugins and sometimes a light version of a DAW . A good software complement is an important part of any audio interface purchase, but particularly so for beginners who often won’t have a huge plugin folder to fall back on. We’re looking to see a good range of EQ, compression, reverb, and delay plugins as well as a free trial for a DAW as a minimum where an audio interface is aimed at the beginner market.

Usability

The crux of our testing process is actually using the audio interface for its intended purpose, to record audio. All of our reviewers have a basic home studio setup at the minimum, which will include an audio interface, studio monitors , studio headphones , and usually a selection of dynamic and condenser microphones . The interface we’re reviewing will replace our personal unit for the duration of the testing period. This allows us to live with it for day-to-day tasks like tracking, mixing, mastering, and even plain old music playback.

We’ll look at how easy it is to access features, like what the buttons on the front panel do, and how they hold up to daily use. Are the inputs easy to access when swapping out microphones? Do the knobs offer enough tactile control? Does it have a dedicated power switch or do you have to remember to turn off your monitors before you shut down your computer? These little things are what a musician will encounter using the interface, making them very important to note down for our review.

We use all the interfaces we test for various recording tasks, whether that's mixing a song entirely in the box, or breaking out the small diaphragm condensers and going Glyn Johns style on a drum kit . We’ll use the interface on our own recordings, noting how they compare to our personal interface as well as others we’ve tested. We might also take the interface out for some mobile recording at a rehearsal or studio space, as a test of its durability on the road.

Another crucial aspect of the usability test is round trip latency. Latency is the time it takes for your interface and computer to process you pressing a key or hitting a pad, to your speakers playing back the sound. We test the latency by using it with a MIDI keyboard or electronic drum kit , setting the buffer size to the minimum, and testing how responsive it is. It is important to note that this is also partially affected by the specs of your computer or laptop, so latency figures may differ. Ultimately we want to see that the interface can provide usable latency on both older and newer machines.

Using the interface is the core part of our review process, and one of the biggest deciding factors in how suitable it is for its intended purpose. Typically we’ll take at least a couple of weeks with any given interface to ensure we get a good overview, many times even longer. This helps us get over the ‘new gear’ phase when you buy something new, and are a little blinded by how shiny it looks on your studio desk .

Sound

Sound is of course a very subjective thing, so it’s not a core part of our review process. The main reason for this is that modern audio interfaces are remarkably similar when it comes to sound quality, with the deciding factor being the end user. That said, some interfaces do certain things better than others so we do look at the sound in one particular aspect, the noise level.

A good measure of an audio interface’s quality is the noise level or as it’s technically known, the Equivalent Input Noise level. Noise levels are inherent in digital equipment, but some interfaces are noisier than others. Getting a truly accurate test of an audio interface’s noise level without specialist equipment is tough, but we test an interface at home by using an XLR dummy load and measuring the meters in our DAW.

We'll also test how well it responds to noisier microphone types like condenser mics, measuring the levels when plugged in with the gain cranked up. A spectrum analyzer (we like Voxengo SPAN ) can give you a reading of the noise level from within your DAW, or you can just test it by using it to record a quiet source.

This second method does present several issues, as noise can come from the room, the mic, the cables, and anything else connected to the interface, so it’s not 100% accurate. It will let us know if the interface has a noise level that could potentially cause issues when recording, and can be useful if we find the recording quality to be unsatisfactory.

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