The series starts with the compact Apollo Solo interface, available in both USB (for Windows systems) and Thunderbolt 3 (for Apple systems) versions. Apollo Solo features a no-nonsense I/O configuration. It has two pre-amplifier inputs with Universal Audio's proprietary UNISON technology which can, almost magically, make them sound and behave like a variety of classic solid-state and tube amplifiers or unbelievably realistic guitar and bass amp emulations in real-time. A high impedance input for guitar signals is also available as an alternative on the first channel. The interface has two outputs, plus a dedicated headphone monitor output. This streamlined amalgamation of inputs and outputs makes Apollo Solo a perfect solution for artists and producers that work in smaller project studios, but don't wish to compromise on sound quality. Moreover, the interface is bus-powered, which makes it extra suitable for the creatives who travel or spend a lot of time working on the go.

Those of us who still value portability in an interface, but require extended connectivity options can confidently make a move towards Apollo Twin X or Apollo X4. Twin is very similar to Solo, but it offers two more output channels, and an optical input for external channel expansion via S/PDIF or ADAT. Apollo Twin X also comes in DUO or QUAD variety, with names indicating the number of DSP cores (versus the single core in, say, the Solo model). Apollo X4 takes it up a notch with four pre-amp inputs (Hi-Z alternatives on channels 1 and 2), six analog outputs, two headphone monitoring outs, as well as optical input and output ports—and four DSP cores.

Apollo X6 features two UNISON mic preamps / Hi-Z inputs, six line-level inputs, eight analog outputs, S/PDIF I/O via RCA plugs, and a pair of optical input and output ports. Apollo X8 differs in that it has four preamps (with Hi-Z on channels 1 and 2), eight line inputs, and ten analog outputs. The configuration on Apollo X8p is slightly different, as it maximizes the preamp count with eight UNISON-enabled channels—each with dedicated combo jack inputs for mic or line level input (and again, Hi-Z on channels 1 and 2). It additionally offers line input via DB25, and all line outputs are accessed via DB-25 ports. This helps in preserving the same sleek 1U form factor while increasing the channel count of the interfaces.

This is also the case with Apollo X16, which offers all of its sixteen analog inputs and sixteen analog outputs via DB-25 connection, and in place of optical ports, this interface provides digital connection via AES/EBU standard. So, while it does have XLR main monitor outputs, all other I/O needs to be handled via DB25 breakouts or connection to external patchbays/500 Series racks/etc. It's important to note that, as such, X16 also foregoes the Unison preamps found on other models, and only features line-level input: so if you're a studio using outboard preamps or 500 Series pres as a frontend for recording, it could be a perfect choice. It is also important to note that all of the rackable Apollo interfaces feature Word Clock I/O and two Thunderbolt 3 ports.

One of the main features that the Zen Tour (and other "Synergy Core" interfaces) offers is onboard processing, courtesy of two FPGA chips and four DSP chips. You have to use Antelope's library of plugins designed for the architecture, however, the list is quite robust and growing. There are several different ways to route these effects in. First, like standard external hardware you record the sound of the compressor, EQ, or channel strip directly into the track, "baking it in." You can also use virtual routing to send your entire project through a mastering setup you have concocted or create individual busses that can be routed to these effects. You can also use their afx2daw plugin which gives you access to the effects just like a VST. It is important to note that when you use these effects, you have to render the audio file in realtime.

Expandability is also a feature with the Zen Tour which gives you independent ADAT and SPDIF connections so you can easily connect it to other pieces that use this format, however, using a DB25 breakout cable, you have eight independent balanced line outputs, all of which are DC-coupled. If you use modular equipment, you can now use Ableton's CV Tools, Expert Sleepers software, and other programs that let you generate CV from your computer. Do keep in mind that because they are balanced you will need floating ring cables to properly access the CV signals.

Recently updated, Antelope Audio's Discrete Pro line of audio interfaces pairs console-style input preamps with their highly regarded converters, clocking, and Synergy Core technologies. The smaller of the two interfaces in this family, the Discrete 4 Pro Synergy Core, is compact enough to sit on a desk or slip into a mobile recording rig, but don't allow its size to cast any doubts on its capabilities. Four discrete preamps with a six-transistor design provide a dash of analog flavor, while a set of four auxiliary line outputs offer options for routing out to hardware pieces, alternative monitoring, and more. Besides your choice of USB or Thunderbolt 3 connection, there are also dual word clock outputs, ADAT optical I/O, and S/PDIF I/O for easy expansion when you need more recording channels.

Of course, if you need a bit more, Antelope's Discrete 8 Pro Synergy Core offers twice as many preamps as its smaller counterpart, but there's more to the story than the channel count. While the eight line outputs have been condensed down to a single DB25 connector, the Discrete 8 Pro offers two dedicated reamp outputs on 1/4" TRS jacks. These outputs allow for impedance-correct processing of guitar or other instrument signals through amps or effects, but can also be used as a secondary pair of monitor outputs. The Discrete 8 Pro also supports more ADAT channels, and boasts additional word clock outputs to further tie your studio together.

Antelope Audio's offerings extend well up into the professional ranges that top studios require, and that includes audio interfaces like the Orion 32+ | Gen 3 and Galaxy 32 Synergy Core. As far as specs are concerned, these are both highly stacked interfaces with abundant analog I/O on D-SUB 25 connectors, Antelope's pristine Acoustically Focused Clocking technology, as well as onboard effects processing with the Orion's FPGA platform and the Galaxy's Synergy Core implementation. But while they might seem similar, each of these interfaces fits into its own niche.

Based on the name alone, you might think the Orion 32+ | Gen 3 is a 32-channel audio interface, and while it is when connected via USB, grab a Thunderbolt 2 cable and that channel count doubles to 64. Channels aside, you'd probably want to use Thunderbolt anyways because by leveraging the Orion's premium AD/DA converters and expertly engineered drivers it's possible to achieve ultra-low roundtrip latency while tracking into your DAW. Couple this with additional digital connectivity via MADI, ADAT, and S/PDIF I/O plus dual Word Clock outputs, Orion 32+ can handle anything that you throw at it.

Our current favorite from Prism Sound's lineup is Titan: perhaps one of the classiest interfaces that we sell altogether. Boasting the same world-class converter technology as its smaller siblings, the Titan ups the analog I/O count to two 1/4" instrument inputs, four mic/line inputs with high-quality preamps, four additional line inputs, and eight analog line outputs. It still affords ADAT optical input and output, so you can double the I/O count if desired; and of course, it maintains the BNC word clock connectivity of the Lyra 2. If even offers an expansion port for connection to PTHD or Dante systems, and it's fully compatible with Mac or PC recording systems.

It's difficult to describe just how impeccable the Titan's conversion is—but rest assured, we'd feel comfortable recommending it for any recording scenario. So if you're an audio archivist, or if you're building a top-notch recording studio, or if you just need to be sure that your project studio has the best sound possible at all times—Titan is a stellar choice.

A big draw for the iD44 MkII is its rich analog circuitry, pulled straight from Audient's premier recording console designs. The four mic preamps are quiet and noise-free, but also provide a subtle flavor of analog warmth. Furthermore, the two instrument inputs feature JFET stages, emulating the behavior of tube amplifiers that have historically been the top choice for guitars and basses, but will work wonderfully on synths and other instruments, too. The first two channels also sport insert loops, meaning that you can place outboard effects like compressors and EQ after the iD44's preamps but before the converters. This is also a great way to get line-level signals into your DAW without coloration from the preamp.

Like any great interface, the iD44 is also highly expandable, thanks to its inclusion of optical I/O ports. Functioning as either S/PDIF or ADAT, you can add up to an additional 16 channels of audio to your interface! If you have a collection of existing preamps that you'd like to incorporate or see yourself needing more options down the road, iD44 MkII is an interface that can grow with you. There's also BNC Word Clock output to sync up other devices in your studio which require it.

On the surface, the UltraLite-mk5 is already an impressive audio interface when only considering its physical specs. Two front inputs accept microphones, instruments, or line level sources with ease, while six additional line inputs are found on the back. Continuing along the rear are a whopping ten line outputs, which means that you can easily drive a set of main monitors, secondary monitors, outboard gear and effects, or any other destination that needs a unique audio channel. As a bonus, like many of MOTU's other interfaces, these outputs are DC-coupled and may be used to drive control voltages into synthesizers, Eurorack systems, and other CV-hungry devices. Of course, there's also a headphone output on the front for easily-accessible monitoring and cueing.

Believe it or not, there's still more I/O to be talked about on the UltraLite-mk5, at least beyond the analog audio channels mentioned above. The final portion of the rear panel is reserved for digital connections that expand the UltraLite well beyond its own capabilities. S/PDIF and optical ADAT input and output ports bring the total number of simultaneously supported channels to 18 and 22, respectively—a truly incredible number for an interface of this size! For example, if you need more preamps than the two provided on the UltraLite itself, more are easily piped in with an ADAT-equipped preamp. On top of that, MIDI ports mean you can connect your favorite synthesizers, drum machines, and controllers to your DAW through the UltraLite.

The most current generation of one of their most iconic devices, the Duet 3 is a USB-C audio interface with onboard DSP. Offering best-in-class Apogee conversion and mic preamps, this 2-in/4-out audio interface provides up to 24-bit, 192kHz recording quality for clean/clear/articulate recordings that capture your sound perfectly. Using an included breakout cable, you get access to 2x 1/4" instrument inputs, 2x XLR-1/4" combo mic/line inputs, 2x 1/4" balanced outputs, and a front-panel 1/4" headphone output (always accessible, even without breakout cable connected).

The on-board DSP provides access to low-latency recording and access to Apogee FX, much in the style of the aforementioned Universal Audio and Antelope interfaces. Of all of the options we've mentioned, though, Duet 3 is perhaps the most portable: so if you need a high-quality interface for recording/mixing on the go and don't need a ton of inputs/outputs or all of the bells and whistles of some of the competition, the Duet 3 is a solid, reliable, no-nonsense option with a stellar sound.

If you need the clarity of those Apogee converters and preamps but need additional I/O? Check out the Apogee Symphony Desktop: a compact version of their higher-end Symphony interfaces, designed for small studios, creators, and performing musicians. Like the unparalleled Symphony I/O MkII, the Symphony Desktop has remarkably low-distortion, high-slew rate, fully differential analog op-amps and some of the best A/D conversion in the business. Similar, the A/D conversion is second-to-none—so no matter what, you know that what you're hearing is exactly what you've captured, and exactly what you've mixed.

Symphony Desktop's mic preamps offer variable impedance and up to 75dB of gain, optimized for use with mic, instrument, or line level signals. You'll get no loss of sound, with deep lows and clear highs always cleanly represented. You'll also have access to Apogee Alloy preamp emulations, great for adding the sound and character of vintage pres and consoles to your tone: grit, character, and attitude you won't find elsewhere. As with the Duet, you'll also have access to Apogee DSP, making it easy to track through specialized, high-end plugins with near-zero latency. With two combo mic/line/instrument inputs, two analog outputs, and eight additional I/O via optical ADAT connections, it can either be your on-the-road interface companion or the center of your entire studio.

RME is one of those brands that have earned a stellar reputation among audio professionals by consistently delivering products that excel in quality, reliability, and performance. As such you never have to worry with RME whether a particular model of the interface is compromised in one of these areas. All of the RME audio interfaces boast top-notch AD/DA conversion via the company's proprietary SteadyClock FS technology, up to 24-bit/192 kHz resolution, low-latency operation, clear and nuanced preamplifiers, and all-in-all flawless build quality. Therefore, all you have to think about when choosing an RME interface is simply which particular configuration fits your recording and/or performance needs best.

Let's start with the most compact offering from the company—the Babyface Pro FS. This USB interface is certainly tailored for artists and producers on the go who will appreciate the small footprint of this device. However, don't let Babyface's cute name and petite size deceive you as this audio interface packs a ton of power and functionality. It boasts two analog outputs, a headphone out, and four analog inputs (two preamps and two Hi-Z) but it can be further expanded via digital optical I/O to a total of 24 channels (12 ins, and 12 outs). The interface also features a MIDI breakout port which allows it to function as a MIDI interface. In terms of operability, all of the essential functions of Babyface are quickly accessible via a large encoder, and two buttons on the front of the panel. And the decently-sized display monitor keeps you always aware of input/output signal levels. Babyface is bus-powered, but an external power supply can be connected if you need to use it as a class-compliant device, aka with no drivers installed.

While Babyface is an excellent interface on all accounts, if you are looking for an even wider set of professional features in an interface then it is highly likely that RME's flagship series Fireface has a device that checks all of the boxes. The series starts with the Fireface UCX II, a USB interface that is arguable as portable as Babyface, but sports a number of professional features that put it into very much its own category. In terms of analog I/O UCX II includes two mic preamp inputs, and two high impedance inputs on the front, plus four more line-level inputs on the back of the unit. There are eight analog outputs—six in the rear, and a stereo headphone out on the front which can be reconfigured to output line-level signals. On the side of digital I/O UCX II includes optical as well as AES/EBU S/PDIF ports. Collectively that comes to 20 inputs and 20 outputs—all in an enclosure that can be easily fit into any backpack. The interface also has standard MIDI ports, and a Word Clock BNC connection configurable to act as either an input or an output. And moreover, like all of the interfaces in the Fireface series, UCX II features a DURec USB port which allows you to record audio from all of its channels directly to a USB A flash drive, which can be useful for creating project backups without interrupting your creative workflow or for operating the interface in a stand-alone recorder mode.

Other interfaces in the Fireface series are studio 1U rack format. These are Fireface 802 and Fireface UFX II. These interfaces share the general feature set of their compact sibling, yet, as would be expected, they are primarily augmented in the channel count area, and in some cases connectivity protocols. UFX II and 802 offer 30x30 I/O. They feature four high-end preamp inputs on the front, and 8 line-level inputs on the back, as well as a total of 12 analog outputs (including 2 configurable stereo headphone inputs). In terms of connectivity, UFX II and 802 pair with computers via USB 2.0 or Firewire connections.

The base model AudioFuse Rev2 is a small cube that has a ton of I/O: on the front you have two combo-jack DiscretePRO preamps and two independent headphone jacks. Around the back you have an extra pair of 1/4" inputs, four 1/4" outputs, two inserts for outboard gear, dedicated Phono input for a turntable, 1/8" MIDI I/O, SPDIF and ADAT, as well as a three port USB hub. Using the well-planned interface, you can easily adjust your levels and the headphone outputs have independent level controls and can function a Cue channels if you use this for DJing. The AudioFuse can also function in bus-powered mode which does reduce the overall signal level to +18dB, but all inputs and outputs are available.

A step up is the AudioFuse Studio, which uses similar design language and expands on everything good the original. With all the same connectivity, the Studio version expands the number of combo, Discrete PRO preamps to four, gives you two reamp outs, extra ADAT I/O, and Bluetooth connectivity. Boasting ultra-quiet preamps with a huge amount of gain, any type of mic in just about any situation will yield high quality sound that is whisper quiet. Each of the four preamps feature a PFL Listen button that lets you isolate the sound before adding into the project, making debugging or sculpting remarkably easy.