How To Buy An Audio Interface

Audio Interface is the centre of every studio workflow. All of your studio gear revolves around an audio interface. Everything communicates with your audio interface, whether it's a computer or a hardware sequencer, a studio monitor or a connected input. 

Audio Interfaces have a lot of power and can greatly improve your studio recording, playback and workflow abilities. 

It is critical to get the right audio interface that meets your studio requirements and supplements your workflow. Hence, buying the right audio interface for your studio setup is critical.

In this article, I have broken down the process of How To Buy An Audio Interface according to your requirements and needs. I will share with you what are the critical aspects to look for when you buy an Audio Interface. What specs really matter and what specs are just a marketing gimmick.

Suggested Read: Best Audio Interface For Home Studio In India

How To Buy An Audio Interface

How To Buy An Audio Interface

To buy the perfect audio interface for your studio requirements and workflow, you need to consider the following points: -

  1. Audio Interface Connectivity: – Do you require a USB, Thunderbolt, Firewire, or a PCIe connection.
  2. Input & Output Requirement: – Input and output requirements caries according to your use and workflow. You need to figure out how many I/O you require before you can get the right audio interface.
  3. Hardware and Specifications: – Hardware of an Audio Interface like the Preamps, Convertors etc. are the core factor on which an audio interface performance depends. Knowing the right specifications to look for while purchasing an audio interface is critical.
  4. Features: – What are the features you require the most in your Audio Interface? Do you require a loopback or not? Do you need an assignable scroll wheel? Do you require a starter software bundle? These are some additional considerations while making the purchase.
  5. Your Budget: – Getting the best value for money is important. With so many options available at a different price point, you need to figure out your budget and get the best possible audio interface according to your requirements.

Audio Interface Connectivity

There are different types of ports available in different audio interfaces When considering an audio interface, the first thing to think about is how you'll connect it to your computer. Determine the type of port connection between your computer/mobile and audio interface.

Most of us think that all we need is a USB connection, but audio interfaces provide a variety of other options, some of which are superior to others. Let's find out the different types of audio interface connections.

Thunderbolt and USB- C 

Thunderbolt 3 or 4 and USB-C are both universally compatible with each other. In fact, you can use a USB-C cable with a thunderbolt port without any issues.

Most audio interface nowadays comes with a USB-C port, which is compatible with Thunderbolt ports. There are specific Thunderbolt ports on some interfaces as well.

The main difference between Thunderbolt and USB-C is that Thunderbolt is a little faster than the USB-C Port.

Overall, Thunderbolt and USB-C are one of the quickest and most dependable modes of connectivity available on today's audio interfaces. They also provide bus power which can make your audio interface power up without the need for an additional power supply.

You should choose between USB-C and Thunderbolt depending upon what your PC, MAC, Tablet, or Mobile supports.

 USB-C Thunderbolt
Faster than traditional USB connections. USB 4 supports speeds up to 40Gbps. USB 3 supports up to 10Gbps. Thunderbolt 3 and 4 support speeds up to 40Gbps.
Widely available on PCs, Macs, Tablets and Mobile Phones. Available on all Apple computers and some PCs
Power and charge devices at 100 watts. Power and charge devices at 100 watts.
Not cross-compatible with Thunderbolt (although they use the same ports). Supports USB as a fallback.

USB 3, 2.0 and 1.1

The most frequent sort of connectivity seen on audio interfaces is conventional USB connectivity. Standard USB interfaces are convenient and simple to set up, although they often have more latency than other forms of connections.

 USB 3 USB 2.0 USB 1.1
USB 3.1 supports speed up to 10Gbps. USB3.0 supports speed up to 5Gbps USB 2.0 supports speed up to 480Mbps USB 1.0 supports speed up to 12Mbps



This is a card-based interface that you connect straight into the motherboard of your computer(internal connection). PCIe performs an excellent job of reducing latency to almost nil and allowing you to monitor/record an almost infinite number of tracks.

PCI Express audio interfaces/sound cards are expensive and used mostly in professional studios.


FireWire was once the industry standard connection type for interfaces.
It was able to transfer data more regularly and was more reliable in general than USB. However, finding an audio interface that supports FireWire nowadays is difficult. They are obsolete, slow and outdated.

Almost no computer nowadays includes a FireWire connection, and FireWire interfaces are only available on used markets.

Audio Interface Input & Output Requirement

The most crucial specification to get right is the input/output (or I/O) count of an audio interface. An audio interface must have a sufficient number of integrated inputs and outputs to allow you to connect your studio gear and instruments to it.

The basic rule of thumb for calculating I/O is one channel equals one input/output.

What you need in terms of I/O depends largely on what you want to do with your studio recordings. If you record using just one mic, get a solo audio interface. If you are someone like me who uses several stereo microphone pairs to record just a guitar, you definitely require a lot more input. If you are a singer-songwriter who writes and records in a home studio setup, you are good to go with just two inputs and one stereo output. If you are a band that jams and records in a basement—you might need somewhere between 8-16 inputs. I/O need.

 Purpose  I/O Requirement To Get Started
Recommended I/O
Recording a Singe/Rapper 1 In and 2 Out 1 In and 2 Out
Singer-Songwriter 2 In and 2 Out 4 In and 2 Out
Electric/Bass Guitar Recording 1 In and 2 Out 2 In and 2 Out
Live Drum Recording 8 In and 4 Out 16 In and 6 Out
Band Recording 8 In and 4 Out 16 In and 6 Out
Djing 2In 4Out 4in 4Out
Podcasting 1 In and 2 Out 2 In and 2 Out


The above table gives you just a rough idea of IO requirements. I/O requirements vary for every different situation, and no one other than you can better judge how many I/O you require.

When buying an audio interface, it is always better to account for your future expansion and additional I/O needs. If you have the budget, adding in a few additional I/O than what you require at present never hurts. Also, look out for expansion features in the audio interface that enables you to expand IO using a digital connection like ADAT. Will discuss more about ADAT in the feature section of this article.

Keep these in mind when calculating your I/O requirements for your audio interface:

  1. One Channel Equals One Input: E.g. To record vocals and acoustic guitar simultaneously, you require one input for vocals and at least one input for guitar. This accounts for two inputs. So you need an interface with at least two inputs.
  2. Account For Your Output Needs: Figure out how many outputs you will require simultaneously. E.g. If you have one headphone pair, one studio monitor and one bookshelf speaker that you use simultaneously, you will require two speaker output and one headphone output.
  3. Account For Your DI Needs: - If you are a guitar /bass/synth player who requires a DI, consider getting an audio interface with a DI.
  4. Account For Additional I/O: - There will always be a time when you will require more inputs and outputs. For such scenarios, it is always beneficial to get an audio interface with a few additional I/O or a digital expansion capability like ADAT or SPDIF.


Audio Interface Hardware and Specifications

It is important to understand that the audio interface is a piece of hardware that really matters. Everything in your studio workflow revolves around the audio interface and your audio interface. If you compromise and ignore the hardware specification and build quality of an audio interface, your production quality will suffer.

Audio Interface hardware and specifications that really matter: -

  1. Preamps

    Preamps or MicPre are the integrated piece of hardware through which you record a microphone signal. Preamps are crucial to your recording signal chain. Mic pres raise levels, particularly in "gain," which can introduce a lot of white noise or high-frequency feedback. As a result, higher-quality preamps tend to add desired warmth to the audio signal rather than unpleasant noise. Crucial specs of preamps to look out for are:
    1. Equivalent Input Noise (EIN)
      This is a measure of how much noise a mic preamp will introduce into a microphone's signal. The more negative the EIN reading, the better, i.e. -130dBm is better performance than -118dBm. Anything less than -125dBm is a good EIN performance for an audio interface. Things to consider while looking at EIN figures are whether the specs are A-weighted or unweighted and what is the impedance of the source used.
    2. Gain Range
      Gain range simply defines the decibels by which you can alter your source signal gain. It’s important that mic preamps have a wide enough gain range to accommodate both the loudest and the quietest signals you’re likely to encounter in recording sessions. If you are recording something with a very soft signal, like an acoustic guitar miked through a passive ribbon microphone, you will need to push that signal more using your preamps. On the contrary, a loud signal like a snare close miked will require less input gain from the preamps and may require some attenuation using the pads to prevent overload. The wider the gain range of the preamp, the more versatile the mic preamp.
  2. Convertors

    Convertors convert the analogue sound signal to digital and vice versa. Convertors are the soul of an audio interface. All of the magic of an audio interface happens in the converters.
    Most modern interfaces convert signals in both directions: analogue to digital (ADC) and digital to analogue (DAC). The better the convertor quality in an audio interface, the better will be your production quality.
    Important convertors specifications to look for are:
      1. Dynamic Range
        The dynamic range is defined as the difference between the loudest and quietest attainable levels. The higher the dynamic range the better it is. Anything between 105dB-115dB is good dynamic range performance. Anything above 115dB is an excellent performance.
      2. Sampling Rate
        Sample rate refers to the number of audio samples carried per second. The sample rate is measured in hertz (Hz) or kilohertz (kHz). The frequency response of the final recording or sample is affected by the sample rate; the maximum frequency that can be correctly captured is 1/2 of the sample rate. Human hearing is from 20Hz-20kHz. So if the audio interface can achieve a 44.1KHz sample rate(CD quality) and 48kHz sample rate(Studio quality) you are good to go.
      3. Bit-Depth
        Bit Depth refers to the resolution of the sound data captured and stored in an audio file. Regardless of sample rate, the number of bits in each sample determines the theoretical maximum dynamic range of the audio data. Each additional bit increases the dynamic range capability of the audio by 6 dB.
        So a bit depth of 16-Bit=96dB Dynamic Range and 24Bit=144dB Dynamic Rage. The more the Bit-depth the better. More bits help capture quieter data more accurately.
      1. Frequency Response

        Unless you plan on recording ultrasound frequencies, 20Hz-20kHz is all you need. If your audio interface can record anything below or above that is a bonus.
        1. Round Trip Latency

          Round-trip Latency is the total time taken by an audio interface to process a signal at the input and reproduce it as output. Round-trip latency plays an important role, especially during tracking sessions. The round-trip latency on an audio interface should be minimum.  Anything above 10ms for 48kHz-24Bit is unacceptable.
        2. Headphone Output Power and Output Impedance

          Output power defines how loud can the audio interface drive a headphone. Most audio interfaces lack headphone output power. If an audio interface is not able to drive high impedance headphones with ample volume, you will require an additional headphone amplifier.
          Output impedance on the other hand specifies how transparent the frequency response would be for outputs. The transparent frequency output is a must for mixing music. Output Impedance should be low, closer to zero the better.

        Audio Interface Features and Additional Functionality

        While buying an audio interface it is important to consider the additional features that the audio interface provides. Different audio interfaces provide different features. Some will provide a great software bundle while others might provide a talk-back. What features you require completely depend upon your studio workflow.

        Here are some important features to consider while buying an audio interface:

        1. Additional Hardware Features: Some audio interfaces provide additional hardware features like an onboard EQ, Compressors, DSP, talkback etc.

        2. Metering: Some audio interfaces provide clip metering while others provide a step metering for levels and gain. Take into consideration how important this is for you, especially during the gain staging process.
        3. Loopback: The Loopback feature allows you to record computer audio directly using your audio interface. This feature is a must for streaming, screen recording, making DAW tutorials and similar purposes.

        4. Digital Expansion: Will you ever require a lot more IO in future. If so it is always good to go for an audio interface that provides the option to expand using an ADAT or SPDIF. ADAT is an optical audio standard for sending and receiving digital audio between two audio devices. ADAT can carry eight channels of uncompressed digital audio to and from an interface and peripheral device.

        5. Included Software Bundle: If you are just getting started, it will be worthwhile to consider the software that is provided alongside the audio interface.

        Your Budget

        If you feel you are on a limited budget and there is too much to trade off than what you need, it is always better to save more.

        There will always be a trade-off. Do not trade-off IO. Pay for hardware first before anything else. If you compromise on the quality of converters or other hardware just because you are limited on budget, do not expect miracles to happen in your production. You get what you pay for.

        To help you get the best audio interfaces in different budgets, I have already done the hard work. Check out my other articles below.

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        Hope this article helped you to understand how to buy an audio interface. If you have any queries, suggestions or feedback please do comment below.

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        Udeeksh Sood on

        Udeeksh is an Audio Engineer. He loves to produce music, research music gear, play guitar, go on treks and road trips.