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SSL 2 & 2+ MkII

USB Audio Interfaces By Sam Inglis
Published October 2024

The buttons on each input channel now have associated LEDs, and the third of them now introduces a high‑pass filter.The buttons on each input channel now have associated LEDs, and the third of them now introduces a high‑pass filter.

SSL’s desktop interfaces get a well‑deserved overhaul.

When Solid State Logic launched their 2 and 2+, some four and a half years ago, they seemed like quite a big departure for a manufacturer best known for boat‑sized mixing consoles. For a fraction of a percent of the cost of the flagship Duality desk, these wedge‑shaped boxes promised the “SSL sound” in a desktop format accessible to anyone with a spare USB port. Unsurprisingly, they took the market by storm, and have proved enduringly successful.

I reviewed the 2 and 2+ back in April 2020 (www.soundonsound.com/reviews/ssl-2-plus), and although they were SSL’s first foray into the world of affordable audio interfaces, found them to be well thought‑out and rounded products that offered “a compelling balance of form, features and audio quality at highly competitive prices”. Indeed, I’ve been using a 2+ as a portable laptop‑based recording device ever since, and can add that it’s proved reliable as well as capable.

No product is flawless, of course, but inasmuch as the 2 and 2+ had limitations, they mostly represented understandable design choices. For example, the second output pair was on unbalanced RCA phonos rather than balanced jacks: not my own preferred option, but undoubtedly convenient for some applications. And the 62dB gain range on the mic preamps was weighted towards the upper end of the scale, offering plenty of clean gain for spoken‑word recording and the like, but limited headroom for very loud sources. Again, this makes good sense, given that an interface with only two inputs is unlikely to get used for close‑miked drums.

Two By Two (Plus)

The original 2 and 2+ have now strolled off into the sunset, and in their place we have MkII versions of both. Given the popularity of the originals, it’s perhaps no surprise that SSL haven’t made any radical changes, but there are numerous small improvements both inside and out.

The new units occupy wedge‑shaped cases that are very similar to those of their forebears, but marginally taller. At first glance, the top panels look almost unchanged, with the same complement of buttons and knobs. You get a large main volume control, plus separate volume controls for the headphone output(s) and a Mix knob that sets the direct monitor balance between inputs and playback. As before, this has an associated Stereo button that selects whether you’d like to hear the direct feeds from the inputs hard‑panned or centrally panned.

There have, however, been some subtle but worthwhile changes to the inputs themselves. On the original 2 and 2+, each input was accessed through a single combi XLR/jack socket. High‑impedance mode for DI’ing instruments was engaged by plugging your guitar into this socket and pressing the Hi‑Z and Line buttons together. The new versions still feature rear‑panel combi sockets for each input, but these are now used only for mic and line‑level sources. Guitars, basses, electric banjos and the like plug into a dedicated pair of quarter‑inch jacks, conveniently located on the front panel. These sense when a plug is inserted and take over automatically from the rear‑panel combi sockets; consequently, the Hi‑Z button on the MkI interfaces is no longer necessary.

Rather than remove this button altogether, though, SSL have repurposed it to add an extra feature in the shape of a switchable high‑pass filter. This complements the existing 48V phantom power, mic/line selector and 4K Legacy buttons, the last of which still engages a combination of saturation and high‑frequency boost that is said to emulate the sound of classic SSL 4000‑series consoles. The three smaller buttons have also been changed from latching to momentary action, with LEDs added to visualise the status of the various settings. This is definitely a valuable change, as the position of the latching buttons wasn’t always obvious at a glance.

It seems I wasn’t the only 2+ user who didn’t love the RCA phonos, because the rear panel now sports four balanced jack sockets carrying outputs 1‑4. What’s more, both interfaces now have two headphone outputs; as before, the second headphone output on the 2+ can optionally be switched to pick up the signal routed to outputs 3+4 instead of the first pair, whilst the new headphone output on the 2 is a duplicate of the first and shares its volume control. In another small but positive development, the headphone sockets have been moved to the front panel.

Elsewhere, the new 2s inherit many features unchanged from the earlier versions. They are bus‑powered over USB, with no option to use a mains PSU, and connect through a Type‑C socket on the rear panel. The 2+ still boasts MIDI In and Out on five‑pin DIN sockets. And, with low‑latency monitoring built in and switched in hardware, there’s no need to install any control panel software. Mac users won’t even need to install drivers, as the 2 and 2+ are still class compliant.

Both of the MkII interfaces now feature two headphone sockets: on the 2, as shown, the second is a duplicate of the first.Both of the MkII interfaces now feature two headphone sockets: on the 2, as shown, the second is a duplicate of the first.

Powers Of Two

There are, though, some fairly significant internal improvements, one of which is hinted at by the bold legending that reads “32‑bit 192kHz”. This signposts that the MkII units employ the latest generation of converter chips, which offer better specs than the originals. Output dynamic range is upped from 112 to 120dB, while there’s now 116.5dB dynamic range on the mic inputs, a 6dB improvement. As with SSL’s PureDrive preamps, however, there’s no practical benefit to recording at 32‑bit. Some USB devices from the likes of Zoom, Rode and Sound Devices use 32‑bit float operation to make their input stages effectively ‘unclippable’; as long as you’re recording at 32‑bit float in a compatible DAW, you can adjust the gain of a clip after the fact to recover from any apparent overloads. That’s not the case with the 2 and 2+, and 24‑bit recording offers more than sufficient dynamic range to capture the full output of the A‑D converters.

If anything makes clipping less likely, it’s the design changes that SSL have made to the mic preamps. These now offer a 64dB gain range and can accommodate signals peaking at up to +9.7dBu, compared with +5.5dBu on the earlier iteration. The superb A‑weighted equivalent input noise figure of ‑130.5dB is retained, meaning these are still some of the cleanest mic preamps around, and perfectly suited to the tasks such as tracking vocals and acoustic instruments that they’re likely to be put to. Should you wish them to be less pristine, the 4K Legacy button still adds a quite obvious treble enhancement, which can be just the ticket on some sources, and a bit much on others. The new high‑pass filter is an 18dB/octave affair turning over at 75Hz, and does its job very effectively, eliminating unwanted thumps and rumbles and thinning out overly heavy close‑miked recordings.

Finally, although the 2 and 2+ still only have one pair of physical inputs, your DAW now sees an additional pair of loopback inputs. This is now a pretty ubiquitous feature in small audio interfaces, and while it’s perhaps not all that useful in most music recording scenarios, it can prove invaluable for streaming, podcasting, vlogging and the like, where you need to feed the output from one software application into another. Some other small desktop interfaces go much further to cater for live streaming than simply providing loopback inputs, offering novelties such as OTG inputs for phone and tablet integration, or Bluetooth connectivity. SSL haven’t followed this path, and that is fine with me: such features are of limited value in music recording, and if that’s your main interest, you probably don’t want to be paying for functionality you won’t use.

I already really liked the 2 and 2+, and I can’t fault any of the changes that have been made in the MkII versions.

If this review makes it sound as though SSL haven’t fixed anything that wasn’t broken, then, that is indeed very much the case. I already really liked the 2 and 2+, and I can’t fault any of the changes that have been made in the MkII versions. I’m not sure that the improvements to the audio specs will make a noticeable difference in the vast majority of cases — if you’re actually recording sources that have a dynamic range of over 100dB, you probably won’t be doing it with a laptop and a stereo bus‑powered interface — but it’s confidence‑inspiring to know that you’re not compromising your sound between mic and DAW. Whilst individually small, changes such as the separate guitar inputs, the LEDs indicating button status and the 2+’s extra pair of jacks offer a real improvement to the user experience, and make for a very worthwhile refresh.

Summary

This well thought‑out revamp will help SSL’s 2 and 2+ retain their status as popular favourites for portable recording and small studio applications.

Information

2 £215.99, 2+ £287.99. Prices include VAT.

Headline Audio +44 (0)1908 477142.

www.headlineaudio.com

www.solidstatelogic.com

2 $229.99; 2+ $299.99

www.solidstatelogic.com