A used interface records just as well and costs a lot less. Which ones to buy, and how to check they'll still run on your computer.

Usually, if it's USB and the maker still lists it. Focusrite lists every Scarlett from the 1st Gen on as working with macOS Tahoe 26 on Intel and Apple silicon, and on Windows 11. The bigger 1st Gen models (6i6, 18i8, 18i20) still pass audio as class-compliant devices but lose their Mix Control app. MOTU's current installers cover the M-series, UltraLite-mk5 and its AVB boxes. FireWire is the dead end, since Apple dropped it in macOS Tahoe. As of October 2026, Focusrite and UA were still testing macOS 27, so check before you update.

Ask for a photo of the underside. Focusrite puts the serial number there, and its prefix gives the generation. V or W means 2nd Gen, and 3rd Gen serials start Y7, Y8, D8, F8, F9, P9, P7 or P5. 4th Gen uses S1, S2, S4, S6, S8, S0, T1 or T2, while 1st Gen starts with U, S or T, so use the socket to split those two. A USB-C socket means 3rd or 4th Gen, and 1st and 2nd Gen 2i2s have a square USB Type-B. Air buttons mean 3rd or 4th Gen. Auto Gain and Clip Safe mean 4th Gen.

Some do. A used Apollo registers to your UA account with UA's free Analog Classics collection, and the seller can also transfer their whole UAD plug-in library, all or nothing. Focusrite's bundled software follows the serial registered in the first owner's account, and the seller has to ask Focusrite support to de-register it. PreSonus doesn't transfer software it gave away with hardware, such as Studio One Artist. Ableton lets a secondhand buyer request a Live Lite serial when the hardware qualified for one. Agree what's included with the seller before you pay.

Ask for a short video turning each gain knob end to end with a mic plugged in. The level should rise smoothly with no crackle or dropouts. Then test 48 V phantom power with a condenser mic on every input. Some boxes switch phantom per input, like the MOTU M2 and UltraLite-mk5, and some use one button for both, like the AudioBox USB 96. A Scarlett 4th Gen mutes the input for three seconds after you switch 48 V on, which is normal. Finish with the headphone output and both main outputs.

Small interfaces run on USB bus power. The Scarlett Solo, 2i2 and 4i4, MOTU M2 and M4, AudioBox USB 96 and Studio 24c need nothing else. Bigger ones won't run without their supply. The Apollo Twin MkII takes 12 V at 1.5 A, centre positive, on a 5.5 by 2.1 mm plug, and UA says a replacement has to match the voltage, current and polarity exactly. A generic adapter with the wrong voltage or a reversed centre pin risks damaging the unit, so pick a listing that shows the original supply.

Thunderbolt 2 does, with an adapter. UA supports the Apollo Twin and Twin MkII on macOS Tahoe 26 through Apple's Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter, with a proper Thunderbolt cable. FireWire doesn't. Apple removed FireWire support in macOS Tahoe, UA lists FireWire Apollos and Thunderbolt to FireWire adapters as incompatible there, and Apple no longer sells its Thunderbolt to FireWire Adapter online. FireWire drivers also won't load on Apple silicon. An old FireWire box needs an older Intel Mac on a macOS version its maker still supports.