Audio Interfaces

An audio interface is basically a soundcard. Its job is to convert analog signals such as microphones and guitars, into digital signals, so your computer can handle them.

An audio interface will usually have preamp controls for each channel. Preamps help get the level of the signal right. There's usually some kind of meter which shows if your signal is too weak, or too strong.

You can get an external audio interface that runs on USB , thunderbolt, firewire (depending on your computer), or if you have a desktop, you can plop an interface into a PCI slot.

What audio interface should you get? Well, let's take a look at the important things you'll need in one, and then I'll give some suggestions.

Here's what you'll be looking for . . .

  • Connection Type (USB? Thunderbolt?)
  • Number of inputs (needs to be as high as the number of tracks you'll record at one time)
  • Direct monitoring (solves a lot of problems related to latency)
  • Phantom power (to power condenser microphones)
  • Outputs
  • Loopback functionality (if you stream)
  • MIDI Capability (if you plan to record MIDI)

Let's talk about these one-by-one

Connection Type

If you computer supports USB 3.0, or Thunderbolt, great. USB 2.0 is plenty though, and interfaces tend to be cheaper. 

You're not going to max out the bandwidth on a USB 2.0 connection. USB 2.0 will handle 480 Mbps, which is roughly 300 audio tracks coming in at one time. Recording your accordion and trumpet duo is not going to tax it.

Firewire will work, as well.

PCIe interfaces are generally expensive, and are used in professional recording studios in which a high number of inputs are needed. They're not often found in home studios.

Number Of Inputs

You'll need as many inputs as you need to use at one time.

  • If you want to record a drum kit, rhythm guitars a bass, with scratch vocals to boot -- all live -- you'll need a lot of inputs and mics. Maybe 10-16 inputs needed on your audio interface for this scenario.
  • If you're a folk duo that both play guitar and sing, and you want to record live, you'll want at least 4 inputs (more if you want the acoustic guitars each recorded in stereo).
  • If you're a singer/songwriter who wants to record, but you're not going to record guitar and voice at the same time, one input will do (as long as the input can handle a mic and a guitar). Two inputs might be better, though.

I play guitar and sing, but for recording, I don't do them at the same time. Theoretically, I could get by with one input, as long as it could handle either a microphone or a guitar input. But two is better for me, because I can livestream myself singing and playing acoustic. Also, I can use one input for vocals, and the other for guitar. I just leave the mic and guitar plugged in with levels set. That way, I rarely have to touch them or change anything.

Focusrite Audio Interface

And with two inputs, I can use two mics to record acoustic guitar, in stereo. Or I could, if I had two working mics (which I don't at the moment).

Dual Use Inputs

Some interfaces have inputs that can be used for either microphone cables, or instrument cables. Some have input jacks that can only accommodate one type of connector. Take that into account when you're counting inputs.

Dual Use Connector

Focusrite 2i2 showing dual use connector. It takes XLR (mic) or 1/4" (instrument).

Direct Monitoring

Direct monitoring allows you to hear the sound from your interface, before it goes through your computer, and recording software. Why is this important?


Latency is the time it takes your computer to process the sound and spit it back out. With the best systems, latency will be a few thousandths of a second. That's generally ok. But if you're trying to record a vocal and the latency is longer, it's very disorienting. You don't hear your voice when you sing, you hear it like it's a slap-back echo.

And for super tight, fast metal recording, even a few milliseconds can throw people off.

One solution is to monitor the signal before it goes through your computer. It's essentially zero latency that way. Audio interfaces typically have one of two ways of providing direct monitoring . . .

  • A switch or knob on the interface
  • Software

My Focusrite Scarlett 2I2 has a switch on the front, labeled "Direct Monitor". I have a Rode USB Microphone (it has a built-in audio interface), which has a knob which controls the mix of your mic sound to your computer sound.

Focusrite Face

Focusrite Face Showing Direct Monitoring Switch

Rode USB Mic

Rode USB Mic with Direct Monitoring

Phantom Power

Condenser microphones require a bit of voltage in order to work. If you're going to use a condenser mic (and you should), you'll need phantom power on your audio interface. Phantom power runs 48 volts up the mic cable, to the mic. It's usually labeled 'Phantom Power', '48v', or '+48v'.


My interface has two main outputs. They are left and right outputs to feed my powered speakers. The interface also has a headphone output for . . . You know what the headphone output is for, right? It's for headphones!

That's enough if you're like me -- a songwriter who only records one thing at a time. But if you record multiple people at once, and need different mixes for different people, you'll need more outputs, and headphone amps.

If you have 4 outputs, you can create one mix and send it to outputs 3 and 4, for a mix for your celloist. Outputs 1 and 2 can still go to your speakers and provide a mix for your banjo player via the headphone output.

You'll need a headphone amp for the additional outputs. If you want to record two people at once, you'll also probably need a headphone amp, but you might get by with a splitter. More than two people? Headphone amp, unless some of them can listen in the room, without headphones.

Unfortunately, the early generation 2I2 interface I use, doesn't put out enough level for my headphones. So, I bought a little headphone amp that also gives me the ability to plug more headphones in, should I need to record two or more people live.

It was about $25.

Headphone Amp

I run the headphone out jack from my interface, into the input of the headphone amplifier, with a stereo cable. I can plug in 4 sets of headphones, if need be.


If you stream, you'll need a way to route your audio to the streaming platform. In some cases, it's pretty complex. If an audio interface has loopback capabilities, it makes it easier to route audio from the interface, mix it with other sound sources (such as recording software) and route it to the streaming software.

It's not a deal breaker. I stream without loopback capabilities in my interface. But it was difficult to set up. If you stream, it's easier if you get an interface with loopback capabilities.

Instruments With MIDI Or USB Connections

Let's talk about two use-cases.

1) Let's suppose you have an electronic drum kit and you want to record yourself playing. You'd connect the kit to your computer, and record your performance in the DAW, as a MIDI track. Then you would use the recorded MIDI to trigger drum sounds.

How would you connect the electronic drum kit to your computer? Either via USB, or MIDI.

2) If you have a keyboard part you want to play, you can record it as MIDI in your DAW. This allows you to easily edit the part, and change the sound later.

How would you connect the keyboard to your computer? Either via USB, or MIDI.

If Your Device Has A USB Port

Most modern keyboard controllers and and other devices have USB connectors available. If this is the case, just use an available USB port on your computer to record MIDI.

If Your Device Doesn't Have A USB Port

Older keyboard controllers and other MIDI capable instruments sometimes have only MIDI and audio outputs. In this case, you'll need an audio interface with MIDI, or a standalone MIDI interface.

Keep in mind, you can do lots of MIDI without having MIDI inputs and outputs on your interface. But if you want to play a part in on drum pads or a keyboard that don't have USB, you'll need MIDI inputs and outputs on your interface or a separate interface.

You're probably better off with a standalone MIDI interface, as they're cheaper than the price differential between an interface with MIDI and without.

For recording drum MIDI, you can actually assign drums to the letters and other keys on your computer keyboard (the thing you type on). You can play your parts in, using your computer keyboard. But you might prefer to sit at a kit, or use drum pads and sticks.

You can also draw the notes in with your mouse, in your MIDI editor, in your recording software.

Audio Interface Checklist

Connection Type: _______________ (USB 2.0, USB 3.0, Thunderbolt, or Firewire)

Number of Inputs Needed: _____

Direct Monitoring: Yes __     No __

Phantom Power: Yes __     No __

Number of Outputs: _____

Loopback Needed? Yes __     No __

Interface Recommendations

Audio interfaces have come a long way. Even the budget models have decent preamps these days. Focusrite, Presonus, Audient, Steinberg, Behringer, Mackie, SSL, M-Audio, Motu, and Tascam all make reasonable quality interfaces.

Two-Input Budget Interfaces

I'd go with the Audient Evo 4 if you need two mics at once (which you might, even if you're a solo artist, and you want to record an instrument in stereo). If you need more inputs and outputs, move up to the Evo 8. The ID4 is also good, but you'll be limited to one mic and one instrument level input.

I just checked eBay, and saw a few used Evo 4s for $99-$129, if you can't afford a new one. Audient is making really good interfaces right now. Clean, good sounding preamps. low noise & quality builds.

But you'd be OK going with any two-input interface that meets your checklist, from the brands above.

If You Need MIDI

You're probably better going with something such as the midiplus Tbox2X2 USB MIDI Interface, for about $30, than looking for an audio interface that has MIDI capabilities. MIDI typically adds about $50 to an interface price.

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}