What Does an Audio Interface Do? Discover what and why you need one. Learn how to choose and set up the perfect interface for recording, streaming, or podcasting.
Best Audio Hub tests and reviews audio interfaces. Our articles may include affiliate links and we may earn a commission. Read more about how we evaluate products.
1. Introduction
Have you ever wondered why your microphone sounds muffled when plugged directly into your computer? Or why professional streamers and musicians always talk about audio interfaces?
As an audio expert who’s tested dozens of interfaces, I’ll explain everything you need to know about these essential devices in simple terms.
2. What Is an Audio Interface?
In short: Think of an audio interface as a translator between your microphone or instrument and your computer.
Just like a foreign language translator helps two people communicate, an audio interface converts analog signals (from your mic or guitar) into digital information your computer can understand, and vice versa.
It does the same as your built-in sound card, but it’s very powerful.
3. Why Do You Need an Audio Interface?
Let me share a quick story. Some time ago, I helped a streamer who was frustrated with their audio quality. They had an expensive microphone but were plugging it directly into their laptop. After connecting it through a Focusrite Scarlett 2i2, not only did their viewers immediately notice the difference – crystal clear voice quality with no background noise – but their post-stream editing became much easier too.
The clean, professional-quality recordings meant less time removing audio issues and more time focusing on content.
Here’s why you might need an audio interface:
Better Sound Quality
Your computer’s built-in sound card is like a Swiss Army knife – it does many things okay but nothing exceptionally well.
An audio interface, however, is purpose-built for professional sound recording. The difference is similar to using a smartphone camera to record a movie versus a professional camera.
Professional Connections
Most quality microphones use XLR connections, which your computer doesn’t have. Audio interfaces provide these professional connections, ensuring you can use industry-standard equipment.
Multiple Inputs
Want to record your voice and guitar simultaneously? Or podcast with multiple guests? An audio interface makes this possible by providing multiple input channels.
4. How Does an Audio Interface Work?
Let’s break down the magic happening inside an audio interface:
- Preamps
The preamp is like an audio magnifying glass. It takes the weak signal from your microphone and amplifies it to a usable level.
Better preamps mean cleaner sound with less noise – that’s why interfaces like the M-Audio AIR 192|6 (which we have reviewed) are praised for their premium preamps.
- Analog-to-Digital Conversion (ADC)
Remember our translator metaphor? This is where the science happens. You see, sound travels through air as waves – just like ripples in a pond. When you speak into a microphone or play a guitar, you’re creating these sound waves.
However, computers can’t understand waves directly – they only understand numbers (specifically, 1s and 0s).
This is how a natural wave is represented. It is a wave that moves the air until it reaches our ears. Our eardrums vibrate according to the characteristics of this wave and transmit this signal to the brain to be interpreted.
Naturally, computers don’t have eardrums and this is where ADC comes in. It takes these continuous sound waves and converts them into digital data by taking thousands of tiny “snapshots” of the wave every second.
Think of it like taking a video of those pond ripples – each frame captures a specific moment of the wave. Higher-quality converters (like those in the MOTU M2) take more accurate snapshots, preserving more detail in your recordings.
- Digital-to-Analog Conversion (DAC)
The DAC does the opposite job – it’s like bringing those snapshots back to life as waves. When you play back your recording, the interface takes all those digital numbers and converts them back into continuous waves that your speakers can produce. It’s similar to how a flip book turns individual pictures into smooth motion.
This conversion process is crucial for sound quality. Better DACs (like those found in professional interfaces) recreate these waves more smoothly and accurately than your computer’s built-in sound card. This is why music often sounds better through an audio interface than through regular computer speakers.
5. Essential Features to Consider
When choosing an audio interface, there are several key features that might seem technical at first. Let me break them down in simple terms:
- Sample Rate and Bit Depth
Think of sample rate and bit depth like the resolution of a photo. Just as a higher resolution photo captures more detail, higher sample rates and bit depths capture more audio detail.
Sample rate is like how many frames per second a video camera takes. The standard CD quality (44.1kHz) takes 44,100 “snapshots” of your audio every second. Meanwhile, bit depth is like the color depth in photos – 16-bit is like having thousands of colors, while 24-bit gives you millions.
For example:
- 44.1kHz/16-bit: Good for podcasting and streaming
- 48kHz/24-bit: Great for music recording
- 96kHz/24-bit: Professional-level recording
Most modern interfaces, like the Behringer U-Phoria UMC204HD we tested, support multiple sample rates. However, for most users, 48kHz/24-bit provides excellent quality without creating unnecessarily large files.
- Phantom Power
Imagine phantom power as an electrical “boost” that some microphones need to work – like how an electric car needs charging. When you plug in a condenser microphone (those sensitive ones great for vocals and podcasting), it needs this +48V “boost” to function.
For instance, if you’re using a Shure SM7B (dynamic mic), you don’t need phantom power. But if you’re using an Audio-Technica AT2020 (condenser mic), you’ll definitely need it.
Most modern interfaces, like the Apollo Solo we recently reviewed, include this feature.
- Direct Monitoring
Here’s a common scenario: you’re recording vocals, but there’s a slight delay between when you sing and when you hear yourself in the headphones. It’s like watching a movie where the audio doesn’t match the lips – frustrating, right?
Direct monitoring solves this by letting you hear yourself in real-time, before your voice even reaches the computer. It’s like having a direct line from your microphone to your headphones.
The Universal Audio Volt 2 has particularly responsive direct monitoring – when testing it, we noticed zero delay between singing and hearing ourselves.
- Buffer Size
Think of buffer size like a water tank. A larger tank (buffer) means more stability but takes longer to fill and empty. A smaller tank means quicker response but might run dry occasionally.
In audio terms:
- Small buffer (64-128 samples): Great for recording, but might strain your computer
- Large buffer (512-1024 samples): Better for mixing, but adds more delay
- Sweet spot: Usually around 256 samples for most home studio work
- MIDI Connectivity
MIDI is like a musical language that electronic instruments use to communicate. If you’re planning to use electronic keyboards, drum machines, or other electronic instruments, you’ll need MIDI ports.
For example, with the Focusrite Scarlett 4i4’s MIDI connections:
- Connect a keyboard to play virtual instruments
- Control your recording software with MIDI controllers
- Sync drum machines with your computer
- Input Types and Quantity
Interfaces offer different types of inputs, each serving a specific purpose:
- XLR inputs: Like a professional microphone’s “home port” – secure and noise-free
- 1/4″ inputs: Perfect for guitars and keyboards, like a standard headphone jack
- Combo inputs: The Swiss Army knife of inputs, accepting both XLR and 1/4″ cables
When choosing input quantity, think about your worst-case scenario:
- Solo musician: 1 inputs might be enough for mic or guitar, like Behringer U-Phoria UM2.
- Podcaster with guests: 2 or more inputs would be better for multiple mics, like Presonus Audiobox USB 96.
- Band recording: 4 or more inputs for recording multiple instruments simultaneously, like Focusrite Clarett+ 4Pre.
- Headphone Outputs
A good headphone output isn’t just about volume – it’s about clarity and power. For instance, the M-Track Solo headphone amp, very afordable audio interface, can drive both consumer headphones and power-hungry professional ones like the Sennheiser HD650s without breaking a sweat.
6. How to Use an Audio Interface
Getting started with an audio interface is easier than you might think. Here’s a comprehensive step-by-step:
- Basic Setup
- Connect the interface to your computer (usually via USB or Thunderbolt)
- Install any necessary drivers
Plug in your microphone or instrument
Select the interface in your computer’s sound settings
- Advanced Setup Tips
Configure your DAW preferences to use the interface
Set up custom routing for different recording scenarios
Create monitor mixes for different performers
Save presets for different recording situations
- Pro Tip: Setting Proper Gain
One of the most common mistakes I see is incorrect gain setting. Think of gain like water pressure – too little and you barely hear anything, too much and everything overflows (distorts).
The sweet spot is when your loudest sounds peak around -6dB on your recording software’s meter.
7. Different Types of Audio Interfaces
- USB Interfaces
A USB audio interface will work with most computers and for a wide variety of needs, from recording instruments and vocals to podcasting and streaming. They are the most common audio interfaces available today.
Most popular for home studios, USB audio interfaces offer excellent compatibility and simple setup. The IK Multimedia AXE IO series, for example, are great audio interfaces for guitar, and bass players, I have done an exclusive selection of Best Audio Interface for Bass Guitar: Bassist’s 10 Picks 2025.
They provide reliable performance and great sound quality.
- Thunderbolt Interfaces
These offer the fastest data transfer and lowest latency. The Universal Audio Apollo series showcases the benefits of Thunderbolt connectivity, though they come at a premium price point.
- PCIe Interfaces
Installed directly into desktop computers, these interfaces offer the highest performance but sacrifice portability. The RME HDSPe AIO Pro is a prime example of what PCIe interfaces can achieve.
8. Choosing the Right Audio Interface
Your needs will determine which interface is best for you. Here’s what I recommend based on different use cases:
- Audio interfaces for Streamers
The Vocaster One (check out our detailed review) is perfect for streaming. It’s simple to use and integrates wonderfully with streaming software and connects direct to phones. Moreover, its capacitive mute button and auto gain make it ideal for live broadcasting.
Best Deal
Vocaster One
- Audio interfaces for Musicians
The Focusrite Scarlett 2i2 remains our top recommendation for most musicians. It’s reliable, sounds great, and is built to last. For guitar and bass players, the IK Multimedia AXE IO is outstanding. For more advanced users, the Universal Audio Volt 2 offers vintage-style compression and exceptional preamps.
Best Deal
Focusrite Scarlett 2i2 (3rd Gen)
Best Deal
Universal Audio Volt 2
- Audio interfaces for Podcasters
The MiniFuse 1 is an excellent choice for podcasting. It’s affordable, provides clean, professional sound quality and loopback feature, so you can capture sound from other sources direct into your broadcast.
Best Deals
Arturia MiniFuse 1
9. Common Audio Interface Problems and Solutions
- No Sound Output
First, check if your interface is selected as both the input and output device in your computer’s settings. Additionally, ensure your DAW is configured to use the interface. Sometimes, simply restarting the interface solves this issue.
- Audio Dropouts
These usually occur due to buffer size settings. Therefore, try increasing the buffer size in your DAW settings. Furthermore, close unnecessary background applications to free up computer resources.
- Crackling or Popping Sounds
Often caused by CPU overload or driver issues. As a result, you should:
Update your interface drivers
Increase buffer size
Check for USB/Thunderbolt cable issues
Ensure your computer meets the minimum system requirements
- High Latency
If you’re hearing a delay between playing and hearing the sound, reduce your buffer size in your recording software. Moreover, use direct monitoring if your interface supports it. The Apogee Duet 3‘s ultra-low latency monitoring is particularly effective for this.
10. Future-Proofing Your Setup
When selecting an audio interface, consider your future needs:
Extra inputs for expanding your setup
Higher sample rates for professional work
Multiple outputs for different monitoring scenarios
Expandability through optical connections
11. Conclusion
An audio interface is essential for anyone serious about recording, streaming, or podcasting. It’s the difference between amateur and professional sound quality.
While it might seem complex at first, understanding these basics will help you make informed decisions about your audio setup.
Looking to dive deeper? Check out our detailed comparisons of the best audio interfaces for different budgets and needs. Whether you’re just starting or looking to upgrade, we’ve got you covered with hands-on reviews and practical advice.
12. FAQ
What does an audio interface do for musicians?
It captures the full dynamic range of instruments and vocals, ensuring studio-quality recordings.
Can an audio interface improve my podcast quality?
Yes! It provides better sound clarity, reduces background noise, and allows for professional mic setups.
Do I need an audio interface for streaming?
Absolutely. Interfaces ensure your voice is clear, latency-free, and balanced with other audio sources.
What’s the difference between USB and Thunderbolt interfaces?
USB interfaces are affordable and compatible, while Thunderbolt interfaces offer faster speeds and lower latency for demanding tasks.
Can I use an audio interface with a laptop?
Yes, most interfaces are compatible with laptops. Just check for USB or Thunderbolt ports.
| ALSO REVIEWED
Bassist, guitarist and producer with a long history in bands, I’ve spent more than 20 years immersed in music and gear. When I’m not playing, I’m writing about audio music, studio setups, recording and everything that helps musicians sound their best.