Because an audio interface is the crucial link between your computer and the outside world, it’s important to research your needs carefully—and those needs aren’t just about today, but what you may find necessary tomorrow.
For computer-based recording setups, your main interface choices use FireWire, USB, or Thunderbolt ports. For professional, commercial networks, you’ll be interconnecting devices through Ethernet connections like AVB (Audio Video Bridging) and DANTE (Digital Audio Network Through Ethernet), or options like MADI (Multichannel Audio Digital Interface; see Fig. 1). This article covers audio interfaces for computer-based recording.

1. Check the specs and compatibility.
Make sure the interface is compatible with your computer, so both can work together optimally. Although not necessarily a cutting-edge technology, USB 2.0 is a time-tested and ubiquitous audio interface option, with USB 3.0 and Thunderbolt offering higher performance. FireWire is not recommended going forward, because it’s in its twilight years. Thunderbolt, while fast, is a fairly mature technology on the Mac, but often requires specific chip sets or motherboards for Windows. For example, Universal Audio has tested their Apollo X Thunderbolt 3 interfaces (Fig. 2) extensively, and has support docs on their web site for Windows-based computers that are known to work, the steps needed to configure your computer, and adapters and computers to avoid until further notice.

With any cutting-edge interfaces, always check the manufacturer’s web site and the web for information on compatibility with your particular system.
2. Don’t be too concerned about backward compatibility.
If you have a computer with a USB 2.0 port or a Mac with a Thunderbolt 2 port, but plan to upgrade to a newer computer, you can think ahead and get a USB 3.0 or Thunderbolt 3 interface. Although these won’t deliver the performance that the latest port protocols offer (i.e., a USB 3.0 interface will operate at USB 2.0 speeds with a USB 2.0 port), they’re almost always compatible (although with Thunderbolt, you’ll need an adapter like the Apple Thunder 3-to-2—see Fig. 3), and will be ready for when you upgrade.

But also note that speed isn’t everything. The latency (the delay between sending audio into the interface, and then monitoring it through plug-ins) with a USB 3.0 interface won’t be that much better than a USB 2.0 interface. The main advantage is being able to stream more channels of audio at higher sample rates—so for example, if you’re doing live recording at 96 kHz, you may benefit from USB 3.0. Then again, if you’re a singer/songwriter working solo, USB 2.0 will likely do what you need.
3. Take advantage of the audio interface market’s competitive nature.
The audio interface market is crowded and competitive, so less-recognized names often give high performance at low prices to try to cut into the market share of the “big guys”—like the TASCAM US-20×20 Celesonic USB 3.0 interface (Fig. 4) and the Zoom UAC-8 USB 3.0 interface (both of which can also serve as digital mixers, like many other interfaces).

And there are interfaces that fly “under the radar,” like the QSC TouchMix-30. Created originally as a mixer, when doing live recording it can stream 32 channels into your Mac or Windows computer, and/or serve as an audio interface with DSP and touchscreen operation in the studio. These are just a few examples—there are a lot of choices that may not be obvious until you do a little digging.
4. Check for expansion options.
You’ll always need more inputs than you think you will. On the Mac, it’s easy to aggregate multiple interfaces, and essentially create one giant interface. You can do it with Windows too if you use the native Windows audio drivers (like WASAPI), but most recording enthusiasts prefer the higher-performance ASIO drivers for Windows. Although you can aggregate some ASIO interfaces, like the Roland UA1010, a simpler strategy is to look for an audio interface with an ADAT optical input port. At 44.1 or 48 kHz, you can feed eight channels of audio (or typically, fewer channels at higher sample rates) from an octal mic preamp with an ADAT output, like the MOTU 8pre USB—see Fig. 5).

5. Define your needs precisely before starting your search.
Regardless of what you need, there’s probably an interface that matches your needs exactly. For example, if you have older MIDI gear with 5-pin DIN connectors, you might want an interface that includes those connectors. But if you find the perfect audio interface but it doesn’t have a 5-pin DIN connector, you can use a USB-to-MIDI adapter cable like the Yamaha UX16, or a full-blown interface with 10 MIDI ports, like the iConnectivity MIO10.

Decide whether you need more XLR mic inputs, more 1/4” TRS line inputs, or combi jacks that offer the option to use both; interfaces with the latter may cost a bit more, but be better-suited to your requirements.
Make a list of what you’d like in an audio interface, then browse the Full Compass site—the odds are you’ll find something that fits your needs.