How to Choose an Audio Interface

Reviewed September 2026.

Buy for the number of things that make noise at the same time, and buy from a company that still publishes drivers for a box it shipped ten years ago. Everything else here is smaller than those two, including whatever part of the specification sheet you have open.

Converters and sample rates are what people compare, because they are the only things on the page that are numbers, and one number is visibly larger than another. Read the numbers the makers actually publish. MOTU quotes 120 dB of dynamic range on the outputs of the M4, a small desktop box and not an expensive one, and every other maker on the interfaces page quotes its own. Put them side by side before you let the price tell you which converter is better. The awkward part is that the two things which will actually end your relationship with the box, the count and the driver, appear on no specification sheet at all.

Count what makes noise at the same time

How many sources are producing sound in the same instant, because that is the only number an interface cares about. A songwriter who records a vocal, then a guitar, then a tambourine has made a three track recording on two inputs. The question gets skipped because answering it honestly means saying out loud that you will record one thing at a time for the next two years.

Box	Preamps	ADAT	Price
Audient iD4 MkII	One, plus an instrument DI	No	$199
MOTU M2	Two	No	about $220
Focusrite Scarlett 2i2	Two	No	about $240
MOTU M4	Two, plus two line inputs	No
Audient iD14	Two	Yes	around $350
Behringer UMC1820	Eight	Yes	about $300
Focusrite Scarlett 18i20	Eight	Yes	about $830
SSL 2+ MkII	Two, and two headphone sends		$299
RME Babyface Pro FS			about $850

A voice and a guitar, which is most people

Two microphone preamps, outputs to monitors, one headphone jack. The Focusrite Scarlett 2i2 at about $240 has been the default for a decade because it does the ordinary thing reliably and the software that comes with it gets people recording the same afternoon. The MOTU M2 at about $220 puts a real level meter on the front, so you see a signal go wrong from across the room rather than from a screen.

At this count the box to beat is the Audient iD4 MkII at $199, for the outputs rather than the inputs: a quarter inch headphone jack and a mini jack, so two people can listen at once, and one preamp from a company that builds large format consoles. The second input is an instrument DI, so a voice on the XLR and a guitar plugged straight in is two at once. Two microphones at once is not, and if that is your pair, the Audient iD14 at around $350 adds the second preamp and the socket the rest of this page is about.

The method behind picks like these is in How I Listen.

Put an M4 and an iD14 side by side

The M4 is the MOTU M2 above with two more line inputs and two more outputs. Like the iD14 it is a small desktop box with two microphone preamps, and both will record your voice and your guitar to a standard nobody will fault. One has a small square optical socket on the back. The other does not, and that is the difference that decides which one you still own in three years.

Session two is a drummer. A kit wants four microphones at the minimum and is happier with six. On the M4 the answer is to sell the M4, and you will take a loss doing it. On the iD14 the answer is a Behringer ADA8200 at about $230, eight more preamps over one optical cable, and you are recording ten channels on a box you already own.

The socket is called ADAT, and the condition nobody states when they recommend it is the sample rate. It carries eight channels at 44.1 and 48 kilohertz and four at 88.2 and 96, because a double rate channel takes two of the eight slots. Track that drummer at 48 and the kit and the room both fit. Track at 96 and you have four inputs, which is a kit and nothing else. Decide that before you buy the expander, not on the night.

A band in a room, which is eight at once

If you already know you are tracking a full band, skip the expansion argument and buy the channels. The Behringer UMC1820 at about $300 is eight preamps and ADAT: ordinary preamps, eight of them, which on a drum kit is the correct trade rather than a sad one. The Focusrite Scarlett 18i20 at about $830 is the same count with better metering and two headphone outputs with their own level controls. Above that you are buying build and support.

The driver decides how long you own it

This is the one place in this category where a company's history is worth more than a specification, because there is no specification for it. The last Mac laptop with a FireWire port was the non-Retina MacBook Pro, sold new until 2016, and after that a FireWire interface needed an adapter chain on every new Mac Apple sold. Apple Silicon arrived in late 2020 and required drivers to be rewritten rather than recompiled, and plenty of boxes from the middle of the previous decade never got one. Neither was a hardware failure. Every one of those units still passed audio cleanly on the day it became unusable.

The same driver also decides your latency, which is where the milliseconds actually come from.

So read the maker's download page before the product page, and find the oldest product still listed with a current driver. RME publishes drivers for the Fireface 800, which shipped in 2004. That is the benchmark, and much of why RME costs what it costs: a Babyface Pro FS at about $850 buys a reasonable expectation that the thing still works in fifteen years. MOTU and Audient have long records too.

The headphone output, against the headphones already on your desk

A Beyerdynamic DT 770 Pro comes in 32, 80 and 250 ohm versions, and the 250 is the one people buy without thinking because the box says Pro. A Sennheiser HD 650 is 300 ohms. Either of those on the single bus powered headphone jack of a small interface runs out of level before it runs out of anything else. That is the expensive part. You settle for a volume lower than the one you would choose, the ear hears less low end at a lower volume, and you decide how much bass the mix wants from there. The loud parts go first as well, because the jack cannot swing enough voltage for the transients.

Two numbers tell you before you spend anything: impedance and sensitivity. What headphone impedance means is the long version and do you need an amp is the five minute one. If you own the 250 ohm DT 770, buy the 80 ohm version for tracking, or buy a box with a headphone amp that can do the work. Both are cheaper than mixing on a headphone that is being underdriven, which is a mistake you cannot hear while you are making it.

If anyone else is ever in the room, the iD4 above already gives you two headphone outputs, and a Behringer HA400 off a line output is about $30 when the box you want does not. What $299 buys at the SSL 2+ MkII is the two sends and a second preamp in one chassis, which is the pairing that matters the first time two people are in front of microphones at the same time.

Buying used, and the two things that fail

Interfaces hold up. Nothing inside one wears out the way a fader or a tube does, and a ten year old box that still has drivers is a good buy at half the money. Two things fail, and only one is in the box.

The sockets. Everything in the room plugs into this thing and gets unplugged again, and the combo XLR jacks, the headphone jack and the USB socket absorb all of it. A crackling headphone jack is the common one. A tired USB socket is the one that costs you half a session before you work out what it is. Plug something into every input, send phantom power to every channel, sweep every control, and move the USB cable around while a signal is running.

The support. Open the maker's download page and confirm a current driver exists for the operating system you actually run. A box on a dead bus is worth what somebody still running that machine will pay, and no more.

Got an interface you are done with? We take consignment, or you trade it against something here, any brand.

If you already own a Scarlett

Then the answer is usually nothing. Trading a working two channel interface for a different two channel interface is the most common upgrade in this hobby that leaves you with exactly what you started with. A second microphone would change the recording. A better sounding corner of the room would. A ceiling on channel count is a real reason to buy, and on this page it is the only one.

The short version

Count the sources that make noise at the same time. Buy the smallest box that covers that count and has an optical input, from a company whose download page still lists a driver for something ten years old. Check the headphone output against the headphones you already own before you read a single converter specification.

At two sources the Audient iD4 MkII at $199 covers the most ground for the money: one preamp and an instrument DI, which covers a voice and a guitar but not two microphones. For two microphones and somewhere to grow, the Audient iD14 at around $350 is the smallest box that does it. If nobody else is coming into the room and no drummer is either, the Scarlett 2i2 at about $240 does the job and has done it for years.

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Come and plug it in

The room is at Free River Studios, 215 E. Lewis St #301 in Livingston, third floor, free and by appointment. It is a working studio, so bring the interface you have and the headphones you have been mixing on. An hour with them against something known settles the headphone question above.