Buy a Focusrite Scarlett 4th Gen if you want to control its mixer from Linux, and any class-compliant box if you only need audio in and out. That split decides the best audio interface for Linux more than preamps do, because the Scarlett range has the most complete mixer driver in the mainline kernel.
We ranked seven USB-C interfaces by what Linux can control, then added the kernel each needs and the PipeWire latency settings. We checked every driver claim against the kernel source and every price on Amazon in October 2026. None of the commands below were run on a lab machine for this guide, because our test cluster was offline.
Which audio interface should you buy for Linux?
For most people the Scarlett 2i2 4th Gen is the answer, because it pairs two good preamps with full mixer control and a driver that has been in the kernel since 6.8. The other picks cover a narrower need. Prices are Amazon US bands from the day we checked, so confirm the live price before you buy:
- Best overall: the Focusrite Scarlett 2i2 4th Gen, about $225, with two mic inputs and full control in alsa-scarlett-gui.
- Best for one microphone: the Scarlett Solo 4th Gen, about $160, with the same driver and loopback.
- Best with MIDI and Linux mixer control: the Focusrite Scarlett 4i4 4th Gen, about $310, adding four outputs and MIDI in and out.
- Best class-compliant pick: the MOTU M2, about $200, with LCD meters you read on the unit itself.
- Smallest desk footprint: the Audient EVO 4, about $160, with a kernel mixer driver on the way.
- Best preamps: the SSL 2 MKII, about $250, with two headphone outputs.
- Best for tone shaping on the way in: the Universal Audio Volt 2 Gen 2, about $219.
Only the first three give you software control of the interface itself on Linux today. The rest are class-compliant, so the kernel streams their audio with no extra driver, but any setting that is not a physical button or knob stays out of reach until a vendor or a volunteer writes the code.
How did we pick these interfaces?
We judged each interface on what a Linux user actually gets, not on what the box promises with the vendor app installed. A preamp spec means little if half the routing lives in software you cannot run. So every pick went through the same checks, and each one is something you can repeat yourself:
- The USB vendor ID was searched in the kernel’s
sound/usbquirk tables and mixer drivers on the current mainline tree. - Focusrite models were matched against the supported-device list in alsa-scarlett-gui and the scarlett2 firmware tool.
- Inputs, outputs, gain and sample rates came from each maker’s own spec page.
- Price and stock came from Amazon’s catalog API on the day of writing.
- No interface was plugged into a test machine, so sound quality and round-trip latency are not our own measurements.
We left out the Behringer UMC204HD, a long-time budget favourite on Linux forums, because its standalone Amazon listing was out of stock with no price when we checked. It is a class-compliant box with one current catch: Linux 7.3, and the 7.2 stable updates from 7.2.10 onward, carry a Behringer boot quirk that stops some UMC204HD units (and the UMC404HD, USB ID 1397:0509) from probing at all (failed to read device descriptor: -110 in the kernel log). A fix that skips the quirk for this model is in mainline for 7.4 and should follow in stable updates. Until it reaches your distro, boot an older kernel such as 7.2.9 or a 6.12 or 6.18 LTS kernel.
How do the picks compare on Linux?
Read the “Linux control” column first, because it is the one spec that changes how you work every day. “Full” means a kernel mixer driver exposes routing, mixer, phantom power and input settings as ALSA controls. “Class compliant” means audio streams work, and the front panel is your only control surface:
| Interface | Inputs / outputs | Max rate | MIDI | Linux control | Minimum kernel | Price band |
|---|---|---|---|---|---|---|
| Scarlett 2i2 4th Gen | 2 mic/inst, 2 line out, 1 phones | 192 kHz | No | Full (scarlett2) | 6.8 | about $225 |
| Scarlett Solo 4th Gen | 1 mic, 1 inst/line, 2 line out, 1 phones | 192 kHz | No | Full (scarlett2) | 6.8 | about $160 |
| Scarlett 4i4 4th Gen | 2 mic/inst + 2 line, 4 line out, 1 phones | 192 kHz | Yes | Full (scarlett2) | 6.8 | about $310 |
| MOTU M2 | 2 mic/line/Hi-Z, 2 TRS + 2 RCA out, 1 phones | 192 kHz | Yes | Class compliant | 6.8 (boot quirks) | about $200 |
| Audient EVO 4 | 2 mic/line + 1 inst, 2 out, 1 phones | 96 kHz | No | Class compliant, mixer driver due in 7.4 | Any | about $160 |
| SSL 2 MKII | 2 mic/line + 2 DI, 2 out, 2 phones | 192 kHz | No | Class compliant | Any | about $250 |
| UA Volt 2 Gen 2 | 2 mic/line + 2 Hi-Z, 2 out, 1 phones | 192 kHz | No | Class compliant | Any | about $219 |
Two things stand out. Every interface here records at 48 kHz on any modern distro, so the kernel column only matters for control, not for basic audio. And the three Scarletts are the only rows where Linux reaches the internal mixer today, which is why they hold the top three spots even though the SSL has quieter preamps (-130.5 dBu EIN) and the Volt lists a higher output dynamic range.
1. Why is the Scarlett 2i2 4th Gen the top pick?
It is the cheapest interface with two mic inputs that Linux can fully control. On Linux, alsa-scarlett-gui covers its routing, mixer, input switches and firmware updates.
Focusrite lists two XLR and jack combo inputs with 69 dB of gain and -127 dBu EIN, two balanced line outputs and one headphone output. It runs at up to 24-bit/192 kHz over USB-C on bus power, and the spec sheet counts 4 inputs and 2 outputs at the computer, because two of those inputs are loopback. Auto Gain, Clip Safe and the Air preamp modes are all switchable from Linux, along with 48 V phantom power and the Inst/Line switch.
Its USB product ID is 1235:8219, and the kernel enables the scarlett2 mixer driver for it from Linux 6.8 onward. Focusrite itself says none of its products are supported on Linux, so all of that control comes from an open-source driver by Geoffrey Bennett, which is now upstream. That matters for repairs, not for daily use: the Focusrite support team will not troubleshoot a Linux setup, but the issue tracker for the driver will.
The 2i2 is a good fit for you in these cases:
- You record two sources at once, such as a voice and a guitar, or a podcast guest.
- You want loopback for streaming in OBS Studio without a software patchbay.
- You run Fedora, Arch or Ubuntu 24.04 or newer, which all ship kernel 6.8 or later.
Look elsewhere if you need MIDI or more than one pair of speaker outputs, because the 2i2 has neither. The Scarlett 2i2 4th Gen on Amazon sat at about $225 when we checked.
2. Is the Scarlett Solo 4th Gen enough for one mic?
Yes, if one XLR microphone and one instrument or line source is all you will ever plug in. It uses the same scarlett2 driver as the 2i2.
The Solo has one mic preamp with 57 dB of gain, one instrument or line input, two line outputs and a headphone jack. It runs at up to 24-bit/192 kHz on USB-C bus power. Loopback and the Air modes are there. Auto Gain and Clip Safe are not listed on the Focusrite page for the Solo, and the lower gain ceiling is the real cost: a quiet dynamic mic such as a Shure SM7B may want more than 57 dB, so plan on a quieter room or an inline booster.
On Linux it appears as USB ID 1235:8218. Without the Pro Audio profile in PipeWire, the Solo channels can show up mapped as 4.0 surround, with the loopback pair labelled “Rear”, which confuses most people the first time. The setup section below shows the one command that fixes it. The Solo fits you when:
- You record your own voice for calls, courses or a podcast with no second guest.
- You use a condenser mic or a hot dynamic mic that does not need extreme gain.
- You want Linux mixer control at the lowest price in this guide.
If a second mic is even a maybe, the roughly $65 jump to the 2i2 is cheaper than buying twice. The Scarlett Solo 4th Gen was about $160 on Amazon. For a budget microphone to pair with it, we have reviewed the Maono PD300X, which has both XLR and USB outputs.
3. When is the Scarlett 4i4 4th Gen worth the extra?
It is worth it when you need MIDI, a second pair of outputs, or both. It is the smallest Scarlett with either.
Focusrite specs the 4i4 with two mic and instrument preamps, two more line inputs on the back, four line outputs, a headphone jack and 5-pin MIDI in and out. The computer sees 6 inputs and 6 outputs, loopback included. It draws 1.5 A over USB-C, and Focusrite includes a 7.5 W power supply in the box, which helps on laptops whose USB ports cannot supply that much current.
Four outputs are where alsa-scarlett-gui earns its keep. You can drag a cue mix to outputs 3 and 4 for a performer’s headphone amp while your speakers on 1 and 2 play the full mix, all from the routing window, with no Windows machine involved. The 4i4 shows up as 1235:821a and needs the same 6.8 kernel as the smaller models. It fits when:
- You plug a hardware synth or controller into 5-pin MIDI rather than USB.
- You switch between two sets of speakers, or feed a separate headphone mix.
- You can keep its power supply plugged in, or your USB-C port provides 1.5 A.
It still has only two preamps, so a drum kit or a band needs a bigger interface. The Scarlett 4i4 4th Gen was about $310 on Amazon when we checked.
4. Why pick the MOTU M2 if Linux cannot control it?
Because it has almost nothing to control. Gain, monitor mix and 48 V are all on the front panel, and the LCD meters show levels without any software.
MOTU lists two combo mic, line and Hi-Z inputs with -129 dBu EIN, two balanced TRS outputs mirrored on RCA jacks, a headphone output and 5-pin MIDI. The ESS Sabre32 Ultra DAC is rated at 120 dB of output dynamic range, level with the Scarlett line outputs. The MOTU product page lists only Windows, macOS and iOS requirements, so there is no Linux promise from the vendor at all.
The kernel looks after it anyway. A boot quirk added in Linux 5.6 to stop first-revision M-series units hanging, simplified in 5.11 and lengthened to about four seconds in 6.7, makes the driver wait for that revision to finish starting, and Linux 6.8 added a control-message delay for the newer revision. On top of that, alsa-ucm-conf ships channel-name profiles for the M2, M4 and M6. The catch is loopback: the M2 loopback channels are a feature of its Windows and macOS driver, and we found no source confirming you get them on Linux.
The M2 is a good fit for you in these cases:
- You want every setting visible on the hardware and never want to open a mixer app.
- You care most about playback quality for mixing on monitors or headphones.
- You need MIDI but not the 4i4’s extra outputs.
Streamers who rely on loopback should take the 2i2 instead. The MOTU M2 was about $200 on Amazon.
5. Should you wait for the Audient EVO 4 mixer driver?
Only if you need its software mixer. The EVO 4 already records and plays back on any modern kernel, and its driver work is merged but not yet in a release.
Audient specs two mic and line combo inputs with 58 dB of gain and under -128 dBu EIN, plus a front JFET instrument input, two outputs and a headphone jack. Converter dynamic range is 113 dB, and the unit is 14 cm wide on USB-C bus power. The EVO 4 tops out at 96 kHz, and Audient publishes an explainer arguing that 192 kHz adds little, so the cap only matters if a client asks for 192 kHz files.
On current kernels the EVO 4 enumerates with an incomplete set of controls. A new mixer_evo.c driver, written in September 2026 and pulled into mainline after Linux 7.3 was released, adds channel mute, the monitor cross-fader, the recording mixer and phantom power, so expect it in Linux 7.4 once that ships. The commit says the EVO 8 is not mapped yet, because the author had no unit to test.
The EVO 4 suits you in these cases:
- You want the smallest interface here, for a crowded desk or a laptop bag.
- You record a guitar often and want a dedicated instrument input on the front.
- You run a rolling distro such as Arch or Fedora that will pick up 7.4 quickly.
LTS users on a 6.x kernel will not see those controls for a long time. The Audient EVO 4 was about $160 on Amazon.
6. Is the SSL 2 MKII worth paying for on Linux?
It is if preamp noise and two headphone outputs matter to you. Solid State Logic calls it class compliant, and we found no kernel quirk aimed at the MKII, so it should run as a standard USB audio device.
SSL lists two Neutrik combo inputs with 64 dB of gain and -130.5 dBu EIN, the quietest preamp figure in this guide, plus two front DI inputs, two balanced DC-coupled outputs and two headphone outputs carrying the same mix. It runs at 32-bit/192 kHz over USB-C on bus power, and the Legacy 4K switch adds the SSL analogue colour to each channel in hardware, so it works the same on Linux as anywhere else.
SSL also lists stereo loopback, but we could not confirm whether Linux sees it without the SSL software. Treat it as missing until you have tested it. Stock is the other caution: the newer Amazon listing was marked scarce, and an older listing for the same model had no price at all.
The SSL 2 MKII fits you when:
- You record quiet sources, such as spoken word with a dynamic mic, where preamp noise is audible.
- Two people need headphones at once, for an interview or a lesson.
- You prefer physical switches over a software panel.
The SSL 2 MKII was about $250 on Amazon, the second-highest price here for a two-preamp box.
7. What does the UA Volt 2 Gen 2 give up on Linux?
It gives up the parts of its feature list that live in the Universal Audio desktop software. The audio path itself is USB class compliant, and the kernel has no special entries for it.
UA specs two combo inputs with 60 dB of gain, two front Hi-Z inputs, one stereo monitor output and a headphone jack, at 32-bit/192 kHz on USB-C bus power. Its selling point is Tone Shaping, three preamp modes called Warmth, Focus and Shine, plus Auto-Gain and loopback. UA describes the unit as class compliant on Mac, Windows, iPad and iPhone, and does not mention Linux.
Because UA’s own software does not run on Linux, you get the audio streams and whatever the front panel can switch, and nothing more. We could not confirm which of the Gen 2 features, including loopback, are reachable from the hardware alone. If the tone modes are the reason you want it, check them on the unit in a shop before you commit. The Volt 2 Gen 2 suits you when:
- You also record on a Mac or an iPad and want one interface for every machine.
- You like setting a sound at the preamp instead of with plugins afterwards.
- You can live without any software mixer on the Linux side.
The UA Volt 2 Gen 2 was about $219 on Amazon, and that listing was also marked scarce.
Which kernel does your interface need?
For class-compliant audio, any kernel from the last few years works. For Focusrite mixer control, you need Linux 6.8 or newer for the small 4th Gen Scarletts, because that release added them to the scarlett2 driver and 6.7 had already switched the driver on by default. Older kernels needed a device_setup=1 module option, which you can now forget. The full list is longer than most people expect:
- Scarlett 3rd Gen, the 2nd Gen 6i6, 18i8 and 18i20, Clarett USB and Clarett+ need Linux 6.7 or newer; the small 2nd Gen models have no mixer driver.
- Scarlett 4th Gen Solo, 2i2 and 4i4 need Linux 6.8 or newer.
- Vocaster One and Two need Linux 6.10 or newer.
- The big Scarlett 4th Gen 16i16, 18i16 and 18i20 use a separate FCP driver from Linux 6.14, plus a userspace daemon called fcp-server.
- The Audient EVO 4 mixer controls are queued for Linux 7.4, which had not been released when we checked.
Ubuntu 24.04 ships 6.8, which covers the small Scarletts but not the Vocaster or the big 4th Gen models, so move to its HWE kernel if you own one of those. Debian 13 ships 6.12, which needs a backports kernel for the big 4th Gen models. If you’re weighing an Ubuntu upgrade for this reason, our Ubuntu 26.04 vs 24.04 comparison covers the kernel jump. Check your running kernel and whether the interface is on the bus:
uname -r
lsusb -d 1235:Focusrite’s USB vendor ID is 1235, so the second command lists only Focusrite devices. Product ID 8218 is the Solo, 8219 the 2i2 and 821a the 4i4. Once it is listed, confirm the mixer driver loaded by searching the kernel log for its start-up line and any firmware warning:
sudo dmesg | grep -i focusriteThe start-up line names the series and the USB product ID, for example Focusrite Scarlett Gen 4 Mixer Driver enabled (pid=0x8219) for a 2i2. If that line is missing, your kernel is too old for the model. If it is present but alsa-scarlett-gui shows little more than an MSD Mode Switch, the interface is still in MSD mode, a small read-only disk Focusrite exposes on first plug-in; holding the 48V button for five seconds while you power it on, or a firmware update, turns that off. If the log says the firmware version is too old, update the firmware as shown next.
How do you install alsa-scarlett-gui and update the firmware?
Install three packages from Geoffrey Bennett’s GitHub releases: the alsa-scarlett-gui control panel, the scarlett2 firmware tool and the scarlett2-firmware files. The control panel is not on Flathub, so the deb, RPM or Flatpak file from the project is the way in. Do the firmware first, because 4th Gen units and the Vocaster need current firmware before every control works. The download loop uses curl and wget, so install those first if your desktop lacks them. On Ubuntu and Debian:
for repo in scarlett2 scarlett2-firmware alsa-scarlett-gui; do
curl -s https://api.github.com/repos/geoffreybennett/$repo/releases/latest | grep -o 'https://[^"]*\.deb' | xargs -r -n1 wget -q
done
sudo apt install ./scarlett2_*.deb ./scarlett2-firmware_*.deb ./alsa-scarlett-gui_*.debThe loop asks the GitHub API for each project’s latest release, so you always get current packages. On Fedora, the same loop fetches the RPM builds instead:
for repo in scarlett2 scarlett2-firmware alsa-scarlett-gui; do
curl -s https://api.github.com/repos/geoffreybennett/$repo/releases/latest | grep -o 'https://[^"]*\.rpm' | xargs -r -n1 wget -q
done
sudo dnf install ./scarlett2-*.rpm ./alsa-scarlett-gui-*.rpmThe prebuilt packages are for x86_64 only, so ARM machines build the tools from source. If the install step complains that no file matches, the GitHub API probably hit its limit of 60 anonymous requests an hour and returned no links; wait and run the loop again. The firmware files land in /usr/lib/firmware/scarlett2. Running scarlett2 with no arguments lists each connected interface with its current firmware and says whether an update is available. Then flash it:
scarlett2
scarlett2 updateThe update resets the interface to its default configuration and reboots it, so close your DAW first. It also turns MSD mode off. After that, open alsa-scarlett-gui from your app menu, and you will get the routing matrix, the mixer, input switches, phantom power and level meters in one window. The alsa-scarlett-gui project page keeps the full supported-device list. Settings are stored in the interface itself, so if they reset every time you plug it in, the ALSA restore service on your distro is overwriting them with an old saved state. The project FAQ warns that the same restore can switch phantom power on unexpectedly, which can damage a ribbon mic. Its fix stops the services and deletes the saved state file:
sudo systemctl mask alsa-state alsa-restore
sudo systemctl stop alsa-state alsa-restore
sudo rm /var/lib/alsa/asound.stateDeleting the file matters, because a udev rule from alsa-utils also restores it every time a sound card is plugged in, not only at boot. Your other sound cards keep working, but their saved mixer levels will not come back after a reboot or a replug.
How low can PipeWire latency go?
PipeWire latency is set by the quantum, the number of samples processed per cycle, divided by the sample rate. The default quantum of 1024 at 48 kHz is 21.3 ms per cycle, which is fine for calls and music playback but far too slow for monitoring yourself through plugins. The interface brand barely changes this number, because every pick here talks to PipeWire through the same snd-usb-audio driver:
| Quantum (samples) | Time per cycle at 48 kHz | Typical use |
|---|---|---|
| 64 | 1.33 ms | Live monitoring through amp sims, if your CPU keeps up |
| 128 | 2.67 ms | Recording with plugins on most desktops |
| 256 | 5.33 ms | Mixing and a safe default for a DAW |
| 1024 | 21.3 ms | PipeWire default for desktop audio |
Those are per-cycle figures. Round-trip latency, from the mic input to your headphones, adds the input and output buffers and the converters, so it is always higher. Start by switching the interface to the Pro Audio profile, which exposes every raw channel with no surround mapping or volume handling in the way:
CARD=$(pactl list cards short | awk '/Focusrite/ {print $2; exit}')
pactl set-card-profile "$CARD" pro-audioRun pactl list cards short on its own to see the exact card name, then swap Focusrite in the match for the string your card uses, such as MOTU or Audient; the match is case-sensitive. Next, force a smaller quantum for the current session and watch the result. In pw-top, the QUANT column should read 64 and the ERR column should stay at zero; a climbing ERR count means xruns, which you hear as clicks, so step back to 128:
pw-metadata -n settings 0 clock.force-quantum 64
pw-topSetting the value back to 0 returns control to PipeWire. Once you have found a stable size, make it the default with a drop-in file, so it survives a reboot. PipeWire always runs at the smallest quantum any client asks for, so a minimum of 64 only applies when an app requests it:
mkdir -p ~/.config/pipewire/pipewire.conf.d
echo 'context.properties = { default.clock.rate = 48000 default.clock.quantum = 256 default.clock.min-quantum = 64 }' > ~/.config/pipewire/pipewire.conf.d/10-latency.conf
systemctl --user restart pipewire pipewire-pulse wireplumberAn app can ask for its own size with an environment variable, which is handy for a DAW, because the graph drops to 128 only while that app is running. JACK apps such as Ardour take the request through pw-jack, which comes from the pipewire-jack package on Debian and Ubuntu and pipewire-jack-audio-connection-kit-libs on Fedora:
PIPEWIRE_LATENCY=128/48000 pw-jack ardourThe Ardour binary is versioned on some distros, such as ardour8, so use whatever name your package installs. To measure true round-trip latency on your own interface, patch a cable from an output to an input and run pw-jack jack_iodelay, which Fedora ships in the jack-tools package. The PipeWire performance tuning wiki covers realtime priority and kernel preemption if you still get xruns.
What should you look for in a Linux audio interface?
Start from what you need to change after setup, not from the preamp spec. If every setting is a knob or a button, class compliant is all you need. If the box has an internal mixer you will use, it needs a Linux driver for that mixer, and today that mostly means Focusrite. Before you buy any interface, check these points:
- The vendor or the kernel source calls it USB class compliant.
- Gain, phantom power and direct monitoring are physical controls, or a Linux mixer driver covers them.
- Your distro’s kernel is at least the version the mixer driver needs.
- Firmware can be updated from Linux, or you have a Windows or macOS machine for it.
- The mic preamp has enough gain for your mic, which means 60 dB or more for quiet dynamic mics.
- Your laptop’s USB-C port can power it, or it accepts an external supply.
Firmware is the item people forget. Most vendors only ship updaters for Windows and macOS, and Focusrite is the exception only because the community wrote one. A Fedora forum thread from January 2025 adds one more caution: one owner of a Behringer UMC404HD and an Audient iD14 MKII reported channel maps that came out mixed up. Replies point to alsa-ucm-conf profiles as the long-term fix, and the Pro Audio profile shown above is the first thing we would try, because it drops the surround mapping entirely.
An interface is usually the first audio upgrade on a Linux desk, and the rest of the setup matters too. If you’re also rebuilding the desk itself, we cover monitors for programming, keyboards and mice for programming and KVM switches for Linux, which also carry USB audio between two machines.
Your first-day setup checklist
Work through these in order the day the interface arrives. Each step has a result you can check, and none of them depend on which brand you bought, except the Focusrite-only firmware and control panel steps:
uname -rshows a kernel new enough for your model’s mixer driver.lsusblists the interface, andcat /proc/asound/cardsshows it as a sound card.- On a Scarlett,
scarlett2reports the latest firmware and the kernel log shows the mixer driver enabled. - alsa-scarlett-gui opens with routing and mixer tabs, and your settings survive a replug.
- The Configuration tab in pavucontrol shows the card on the Pro Audio profile with every channel listed.
pw-topshows your chosen quantum and an ERR count that stays at zero while you record.
If all six pass, the interface is fully set up. Most problems we see in forum threads trace back to steps 3 and 5, an interface left in MSD mode or a card left on the default stereo profile, so check those two first when something looks wrong.
