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In this article, we will look at what is an audio interface.

An audio interface is an external sound card that plugs into a computer most often through USB. (There’s also PCI Card Audio Interfaces.. and Firewire Audio Interfaces were quite popular back in the day).

Why you’d want an audio interface for music production is simply to plug in professional music equipment like reference monitor speakers or headphones for listening to music, or recording high-quality audio into your computer with an audio interface by using professional microphones with XLR cables.

An Audio Interface Breakdown

Example of two audio interfaces by the company Focusrite (Scarlett model)
Example of two audio interfaces by the company Focusrite (Scarlett model).
Expensive audio interfaces allow more connectivity (and often better components)

An audio interface is simply an external sound card on steroids!

It plugs into your computer through a USB Cable, which is used for both data and power, and connects high-quality studio speakers, headphones and microphones for studio use.

My favorite audio interface feature is controlling volume from a knob that sits close to you, rather than reaching, or doing it through software.

Depending on audio interface price, the amount of inputs and outputs will differ for connecting equipment like speakers and microphones.

Audio Inputs are for recording audio with microphones, or recording other audio equipment like Keyboards, Drum Machines, or outboard gear like analog compressors and equalizers.

Audio Outputs are for listening to audio, or sending audio into another piece of equipment for processing.. For example, Outputs 1 & 2 are the main LEFT and RIGHT audio. Output 1 is LEFT, Output 2 is RIGHT.

Front of an Audio Interface

Cheap Audio Interface Example (Focusrite Scarlett 2x2 2nd Gen)
Front of an affordable Audio Interface
(Focusrite Scarlett 2×2 2nd Generation)

The front of the audio interface is typically where we plug in microphones to record, control speaker volume, or headphone volume. (However, some brands move some of this to the back).

Because audio interface companies differ so much, it’s more important to understand the basics of an audio interface!

Less-expensive audio interfaces doesn’t mean bad (sometimes they are), but usually affordable audio interfaces provide less connectivity.

Example of a medium-level audio interface with more connections (Focusrite Scarlett 2x4 1st Generation)
A step-up in price audio interface (more connections, not better quality)
(Focusrite Scarlett 2×4 1st Generation)

For example, the front of an expensive audio interface may allow you to record 4 microphones! Whereas an affordable audio interface may only allow you to plug in 1 or 2 microphones!

The very first image under this Front of an Audio Interface section shows two microphone inputs, just like this second image.. (but the more expensive audio interface has a couple extra features on the front, and the back looks very different).

A powerhouse audio interface with lots of connectivity, and is a monitor controller! (Mackie Big Knob Studio Audio Interface)
This audio interface is also a monitor controller to switch between banks of speakers
(Mackie Big Knob Studio Audio Interface)

This Mackie BIG KNOB Studio is a very unique audio interface.

While it provides normal audio interface features like recording microphones, and connecting professional speakers and headphones, it’s also a monitor controller.

Now, a dedicated monitor controller is VERY EXPENSIVE..

So the fact this is both an audio interface and monitor controller, is revolutionary to the audio interface industry!

(This particular audio interface isn’t the highest quality, but the ability to switch between multiple sets of speakers, and its convenient MONO, MUTE, and DIM buttons, this is worth looking at!)

I’d definitely pay for a high-quality monitor controller audio interface combo, which I think would sell like hotcakes!

Otherwise you have to buy an audio interface and a monitor controller separate.. but combining them together is what producers really need!

Cheap audio interfaces may face issues like drop-outs in recordings, noisy pre-amps (what powers the microphone), or cheap hardware components, like crackling sounds when rotating knobs.

Back of an Audio Interface

Back of a cheap audio interface connections (Focusrite Scarlett 2x2 2nd Generation)
The back of a simple audio interface with minimal connections
(1 Pair of Outputs, a LEFT and RIGHT)

The back of an audio interface is typically where speakers connect, or audio is sent to connect to other audio equipment.

When connections are in the back of an audio interface, your studio setup generally looks cleaner, especially if you always use the same microphone setup.

But sometimes front inputs to connect microphones is convenient for workflow if you’re always connecting different equipment.

Back of a medium-level audio interface connections (Focusrite Scarlett 2x4 1st Generation)
An audio interface with more output connectivity, like RCA, MIDI, in addition to 1/4″ Jacks and USB you’d see on affordable audio interfaces.
(Notice 3 + 4 on RCA White and Red outputs.. an extra set of OUTS!)

More expensive audio interfaces usually have more outputs, which many studios take advantage of when sending audio into analog audio equipment like hardware compressors.

My recommendation is to work inside your computer with plugins as much as possible, as it reduces costs, and is easier to work with. Using dedicated pre-amps and compressors are useful for recording microphones, but when hardware mixing, your price-point jumps drastically, takes up a lot of space in the studio and hard drive, and you can’t recall settings..

Back of an audio interface and monitor controller (Mackie BIG KNOB Studio)
An example of an audio interface with lots of output connectivity to connect to multiple speakers or audio equipment.

The most important part of buying an audio interface is figuring out what you actually need, with some room for growth.

For example:

  • How many microphones are you going to plug in?
  • How many sets of speakers will you use?
  • Do you need high-quality pre-amps for the best microphone recording?

Each of these questions will direct your purchasing decision.

So understand, if you’re a beatmaker, which my website teaches, we often only need an audio interface with few connections..

We aren’t connecting 7 microphones to record drum sets.. we may record our self, or an artist, which only requires one microphone input.

But as you advance, you may want a high-quality microphone input so there’s not bad pre-amp noise, and give your music the pristine quality you’re after.

So if you’re going to pay more, a quality microphone input is something to look at, rather than how many microphones you can connect!

Audio Interface Cable Types and Connection Ports

Various Audio Cable Types like TS, TRS, XLR, USB A, USB B, and USB C
Various Audio Cable Types like TS, TRS, XLR, USB A, USB B, and USB C

Let’s cover different audio cable types for audio interfaces with pictures.

Audio interfaces typically have XLR, 1/4″, 1/8″, or RCA jacks.

For more information, read What Cables to Buy for Studio Speakers.

TS Unbalanced vs. TRS Balanced (1/4″)

Typically earbuds have an 1/8″ jack, but typically studio connections are 1/4″ jacks (bigger). It’s also important to understand TRS vs. TS cables, which usually means balanced vs. unbalanced.

Most of the time we want TRS balanced cables when connecting speakers, as they can run longer distances without noise being introduced into the audio signal.

For instruments, TS cables are often used, but typically 10-15 feet max!

TS Cables (Unbalanced Cables)

TS Unbalanced Cable for Instruments like Guitars, and Digital Keyboards
TS Cable. (TS stands for Tip, Sleeve.)
Notice it only has 1 Black Ring!

TS Cables are mainly used for connecting certain instruments, like guitars, keyboards, and vinyl turntables (if they don’t have USB).

These TS Cables are unbalanced, and can only travel short distances, otherwise noise gets introduced into the audio signal.

This is because TS cables only have two wires, and are susceptible to noise at longer lengths. Just remember, TS Cables have 1 Ring, and TRS Cables have 2 Rings! (We most often want TRS Balanced cables!)

RCA Unbalanced Cables
RCA Audio Cables showing Both Male and Female Connection Types
RCA Cables
Left: Male Connections
Right: Female Connections

RCA is just like a TS Cable (unbalanced), but a different connection type..

It’s often used in the audio visual world, which if you’re older, you’ve probably used to connect to a TV before!

In the music production world, RCA is often found on Vinyl Record Players which you’d use to sample music.

But again, just like 1/4″ TS cables (just one ring), RCA cables are unbalanced.

Unbalanced doesn’t mean bad quality audio, it just means cable lengths can’t be overly long, and certain equipment is designed for such cables!

Balanced Cables (Less Noise!)

1/4″ TRS cables and XLR cables are called balanced cables which allow long audio cable distance without noticeable noise!

This balanced cable uses a cool concept by running an extra wire out of phase, then it flips back at time of connection, which cancels out the noise, but not the audio (it’s genius!)

1/4″ TRS Cables
TRS 1/4" Balanced Audio Cables for Connecting to Speakers or Outboard Equipment
TRS Cable. (TRS stands for Tip Ring Sleeve).
Notice it has two black rings!

Most audio interfaces have 1/4″ TRS Balanced Outputs that we then connect to our speakers, or send to other audio equipment.

Usually we use TRS because the audio equipment doesn’t accept an XLR connection. TRS 1/4″ and XLR Cables are the same type of cable (balanced), just a different connection type.

We want to use TRS or XLR to plug in our speakers!

XLR Balanced Cables
XLR Balanced Cables for connecting to microphones, reference monitor speakers, or outboard audio equipment.
XLR Balanced Cables for connecting to microphones, reference monitor speakers, or outboard audio equipment.

XLR Cables are probably the best type of audio cable for a strong connection. XLR cables are balanced, just like TRS 1/4″, meaning we can run them at long lengths.

One big benefit of XLR cables is the female connector often has a click-in connection, locking the cable into the microphone! (If you’ve ever seen a singer swing the microphone, you better thank this locking mechanism!)

We use XLR Cables for microphones, speakers, and various audio equipment..

But it really comes down to if the audio equipment accepts an XLR connection (otherwise we just use 1/4″ TRS Balanced cables).

Audio Interface USB 2.0 vs. 3.0 USB

Audio Interface USB Cable - USB-A to USB-B - Other known as a printer cable
Audio Interface USB Cable
Often used as a typical computer printer cable

Most audio interfaces these days are USB, with the new USB Type-C connection. But remember, USB-C doesn’t mean USB 3.0!

Older audio interfaces used USB-A to USB-B cables (a printer cable).

But surprisingly.. most audio interfaces are still USB 2.0.. so you might wonder, should you buy a USB 3.0 Audio Interface?

Will a USB 3.0 Audio Interface give you better results? Better performance? Better audio?

Most USB Audio Interfaces are still USB 2.0, showing Focusrite Scarlett 4th Gen USB Type-C, but still USB 2.0
Most USB Audio Interfaces are still USB 2.0.
Showing Focusrite Scarlett 4th Gen USB 2.0 Type-C

The short answer is USB 2.0 is still sufficient even in 2024! This is because when recording with an audio interface, we usually don’t take up the full bandwidth available in USB 2.0!

USB Type-C Cable
USB Type-C Cable

But what about audio latency with USB 2.0 vs. USB 3.0 Audio Interfaces?

Well, audio latency is still a problem..

But in short, at the moment, don’t worry about USB 2.0 or USB 3.0 audio interfaces.

USB 2.0 doesn’t use the full bandwidth when recording.. (especially if recording 2 microphones).

At the moment of writing, what I would focus on for an audio interface is low-latency, and good microphone pre-amps and headphone amps. I’d also make sure to get a USB Type-C so it’s future proof for years to come.

Audio Latency and Audio Interfaces

The biggest problem with the audio world to date is audio latency.

Audio latency is how long it takes for you to talk into a microphone, the audio to go into the audio interface, be processed by the computer, then come out of the audio interface to your speakers or headphones.

This is known as round-trip latency, and it’s a killer when recording vocals, or even just playing melodies with a MIDI Keyboard.

Thankfully, music production computers have become very powerful, so we can run our music programs at lower buffer size to reduce latency.

And.. audio interface drivers and components have improved, which have also reduced audio latency..

But still, having zero-latency is practically impossible, unless you look into an audio mixer.

Do Audio Interfaces have Headphone Amps?

Yes, almost every audio interface has a headphone amp, but more expensive audio interfaces will make sure to put a high-quality headphone amp in their audio interface.

For example, MOTU really makes a point that their MOTU M-Series Audio Interfaces have special ESS converters for their headphone amplifier!

Wrapping Up: How to Tell Audio Interface Inputs and Outputs (2×2, 2×4, 4×4?)

One of the most confusing things about an audio interface is understanding the terminology of the product you’re buying.

If you see 2×2, that means 2 inputs, and 2 outputs.

If you see 2×4, that means 2 inputs, and 4 outputs.

As you start paying more money, more connections will become available, and the connections may be of better material, which may set moderate audio equipment apart from pro-level equipment.

What audio interface would I purchase today?

Well, I really like having that monitor controller built into my audio interface.. and it’s hard to step away from that..

But I have had my eye on the MOTU M-Series.. MOTU has always seemed to be ahead of the curve with their audio interfaces, but don’t get as much attention as other brands.. if you look at their product specs, I think you’ll be surprised with what they offer!

If you need further help with your music production, try my Beatmaking Courses.