How to choose the right audio interface for your home studio

An audio interface, also known as an “AD/DA converter” or simply an “AI”, converts analog audio signals into digital ones so your computer can use them, and then turns digital signals back to analog so you can hear them through your monitors or headphones.

Audio interfaces are confusing when you first get introduced to them, and if you aren’t sure what features you really need or how to tell a good audio interface from a bad one, you’re definitely not alone.

This guide from Parlor City Sound will provide you with a basic rundown of what audio interfaces do and how they work. And we’ll list off a few of our favorite audio interfaces too, so you have a better idea of what to look for.

What is an audio interface?

Simply put, an audio interface is a device that converts analog audio signals (say, from a microphone or a guitar amp) into digital signals. It then sends those digital signals to your computer, where you can record them using DAW (digital audio workstation) software. Check out our guide on DAWs for more information on what they are and how they work.

The audio interface also converts digital audio signals back into analog signals so you can use them outside of the computer. You could send these signals to your monitors, back to a mixing console, or even to an analog recording medium like reel-to-reel.

Audio interfaces are often referred to as AD/DA converters. The “A” stands for analog and the “D” stands for digital. This is just a fancy way of saying it converts analog to digital and digital to analog. You’ll also find AD and DA converters that only do one or the other.

The three key attributes to look for in an audio interface

Audio interfaces have a lot of crazy features their manufacturers love to rattle off. But there are really just three key features you should really focus on at first.

Inputs allow you to connect microphones and instruments to the audio interface. You need to find an interface with enough inputs to cover your needs. Most audio interfaces have preamps on these inputs, allowing you to provide phantom power to condenser microphones without needing additional equipment.

Resolution describes the sample rate and bit depth the audio interface can record at. Most interfaces can handle multiple resolutions. We’ll discuss this in a moment.

Simultaneous I/O tells you how many input and output channels the interface can handle at the same time. Having more input channels means you can simultaneously track more inputs at once in your DAW. Output channels let you return audio from the computer back to the analog realm.

Some other features that you might want to learn more about:

• ADAT I/O lets you connect multiple devices together and share data across ADAT cables. Some audio interfaces also have ethernet connections for more advanced device networking
• MIDI I/O allows you to connect MIDI devices, like keyboards and drum machines, directly to your audio interface 
• SD Cards let you record audio directly to, well, an SD card. This isn’t a common feature but you’ll find a few audio interfaces that offer it
• Word clock helps you sync up multiple devices together so they’re all processing things at the same time and at the same pace. This is important if you’re running multiple digital devices at once. But a lot of home recording studios won’t need to worry about this out of the gate.

MORE: Our beginner’s guide to recording studio microphones

Audio Interface resolutions explained

Audio interface resolutions are probably the most confusing aspect to wrap your head around, for most musicians anyway. Sample rates and bit depths don’t really matter in the world of analog instruments. So let’s learn more about this next.

I once had someone explain sample rates as a camera taking photographs of sound to compile into a flip book. The higher the sample rate, the more photos you’re taking and thus, the more accurate and full of detail your flip book ends up being. 

A sample rate of 44.1 kHz is snapping 44,100 of these photos per second, while a sample rate of 192 kHz is taking 192,000 photos per second. It’s pretty easy to see which is better using this analogy!

Bit rates are a little different. Each bit is equal to roughly 6 decibels (dB) of dynamic range. That means a bit rate of 16 gives you 96 dB of range. 24-bit is even better, with 144 dB.

Imagine, if you will, a box. Sample rate shows you how wide and long the box is, and bit depth shows you how tall it is. The bigger the box, the more it can hold. So when these numbers get bigger, the sound quality gets better.

Of course, filling a larger box requires more energy, and it also means you’ll have a harder time finding things inside it. Higher resolutions put additional strain on your computer, too, so if your machine isn’t high-grade you may have a difficult time recording at these higher resolutions.

Recording at 192 kHz/ 24-bit ensures you’re getting the best sound quality, but few people can hear the difference between 192 kHz and 48 kHz. Your computer will have a harder time capturing that, too. So don’t stress too much about these super-high resolutions.

CD quality resolution is 44.1 kHz. A lot of engineers record at 48 kHz, and 96 kHz is rapidly growing in popularity and access, too. Recording at 192 kHz is fancy, and if your equipment can handle it hey, go for it. But it’s unnecessary to aim for that, especially since your listeners aren’t likely to notice regardless. The benefit of recording at a higher resolution is having more headroom when mixing and mastering later on.

What does simultaneous I/O mean and why does it matter?

Let’s say you’re looking at an audio interface with eight XLR inputs and two outputs. That means it sends eight channels to the computer and brings two back, right? Well … not necessarily.

Simultaneous I/O refers to how many analog signals the audio interface converts to digital at once, and how many digital signals get converted back to analog at the same time.

If an audio interface has 8×2 simultaneous I/O, it will convert eight individual analog signals and send them to your DAW, and it will pull two digital signals from your computer and convert them back to analog. That means you can record in eight DAW channels at once, and you’ll get stereo sound returned from the computer too.

Many audio interfaces are able to connect with multiple devices, including other interfaces, microphone preamps, mixers, digital stage boxes, and more via USB, ethernet, Thunderbolt, or other connections.

It’s not uncommon to see audio interfaces boasting huge simultaneous I/O numbers, like 96×96 for instance. It may only have eight XLR or TRS inputs, but it can take in more channels from other devices by ADAT, ethernet networks, or some other system. This might be useful to you eventually, but most home studios won’t really need that at first.

The audio resolution is (sometimes) a lie 

Now for the annoying part of shopping for an audio interface: marketing people always leave out some of the finer details that really begin to matter once the honeymoon phase with your new gear has lapsed.

Some audio interfaces boast that they record at 192 kHz, 24-bit … but they sort of don’t. That might be their resolution when recording two channels, but when you move up to eight channels you’re suddenly restricted to 48 kHz, 24-bit. It’s not terrible, but it sure does feel like false advertising when you’re buying an AI because of that higher input count.

ADAT has similar limitations too. ADAT can carry eight channels at 48 kHz, but just four channels at 96 kHz and only two channels at 192 kHz. So if you’re expanding your studio with more gear, maintaining higher resolutions gets to be profoundly expensive when using some of these networking options, like ADAT.

Which audio interface should you get?

Ultimately, you’ll want to take this information we provided here, expand on it, and buy the audio interface that’s right for your own needs. These devices are pricey, so take your time with this decision. Shop around. Read reviews. You don’t want to rush into buying an audio interface only to learn it doesn’t do what you need it to do.

Parlor City Sound doesn’t make or sell gear. We don’t make or sell anything, actually. So we want to make some recommendations based purely on hands-on experience, customer reviews, and general value. But there are lots of other audio interfaces on the market. You really should browse them and find one that’s right for you!

Behringer U-Phoria UM2 

• $45
• 2x inputs (1 XLR/ TRS preamp, 1 instrument)
• 2×2 simultaneous I/O
• 48 kHz, 16-bit resolution 

This is a low-frills, super-affordable AI perfectly suited for a solo artist, with one phantom-powered preamp for a condenser mic and one hi-z input for a direct line from your guitar amp.

Behringer U-Phoria UMC202HD

• $90
• 2x inputs (XLR/ TRS preamps with phantom power)
• 2×2 simultaneous I/O
• 192 kHz, 24-bit resolution

A significant upgrade over the UM2, Behringer’s U-Phoria UMC202HD offers two preamps and studio-quality resolution. Great for a solo act, or for recording master outs from a mixer.

Behringer U-Phoria UMC404HD

• $170
• 4x inputs (XLR/ TRS preamps with phantom power)
• 4×4 simultaneous I/O
• 192 kHz, 24-bit resolution

Similar to the UMC292HD, but with double the I/O. It also adds four inserts as well as MIDI I/O, making this the cheapest audio interface we’ve yet seen with a rich roster of features.

M-Audio AIR 192/14

• $330
• 8x inputs (4x XLR/ TRS preamps with phantom power, 2x hi-z, 2x TRS)
• 8×4 simultaneous I/O
• 192 kHz, 24-bit resolution

The M-Audio AIR is perhaps the cheapest audio interface a band should really consider, assuming you’re using a simple drum mic layout. It features four preamps and two hi-z line inputs, plus two TRS inputs. It also has MIDI I/O and four TRS outputs. It’s a very good audio interface in this price range. But don’t buy this until you’ve looked at the next entry!

TASCAM US-16×08

• $370
• 16x inputs (8x XLR preamps with phantom power, 8x TRS)
• 16×8 simultaneous I/O
• 96 kHz, 24-bit resolution

Easily one of our top picks for bands, this audio interface has eight preamps, eight TRS inputs, MIDI I/O, built-in DSP effects, and it mounts in a rack, too. Having eight TRS outputs is pretty darn handy as well. This is a great audio interface for bands running lots of drum mics in a home studio environment.

Presonus Studio 1810 

• $420 
• 8x inputs (4x XLR/TRS preamps with phantom power, 4 x TRS)
• 18 x8 simultaneous I/O
• 192 kHz, 24-bit resolution

This audio interface has fewer preamps, and inputs in general, than the TASCAM. But it does support ADAT, allowing for future expansion, and also has MIDI, DSP effects, and S/PDIF I/O as well.

 Mackie Onyx24  

• $959
• 24x inputs (18x XLR/ TRS with preamps and phantom, 14x TRS)
• 24×4 simultaneous I/O
• 96 kHz, 24-bit resolution

In our humble opinion, the Mackie Onyx24 is the best home studio audio interface for less than $1,000. It’s a full-featured mixer with 18 preamps in channel strips with parametric EQ, panning, and built-in effects.

There are audio interfaces at this price point with more features, better digital connectivity (this mixer doesn’t have ADAT), and even better converters. But the Mackie Onyx24 can get your full band recorded without unplugging a single cable, multi-track or live. And we dig that. We dig that a lot.

Looking for an audio interface? You better shop around

There is an audio interface for sale to suit just about anyone, from a bedroom musician putting together vocal and guitar jams to a semi-professional home studio engineer expanding their equipment to the next level. The trick to finding the right audio interface is simple: shop around.

The audio interface you choose will play a quintessential role not only in your current project, but in future projects as well. And it’s not like an instrument you can test drive and feel out to see if there’s a mystical connection. You’ll want to crunch numbers, review your budget, compare as many units as possible, and ultimately choose what’s going to suit you the best, and for the longest stretch of time too.

We hope this guide explains some of the basics of audio interfaces for you. Our goal here at Parlor City Sound is always to give you valuable information and honest opinions. And hey, if you did like this guide, please check out some of our other free guides too!