Have RME made the perfect USB audio interface?
RME’s Fireface UFX has long been the company’s flagship interface, and I reviewed the very first model back in 2011. At the time, its 60 channels of simultaneous I/O (30 inputs and 30 outputs at base sample rates) was an outstanding feature, and it offered both USB 2 and Firewire 400 connections for hooking up to a computer. Such were the high technical standards of that original UFX that it was six years before its leading position was toppled — by the UFX+, introduced as part of the company’s 20th anniversary celebrations.
In essence, the UFX+ was a UFX melded with a MADIface USB, expanding the original model’s 60 channel I/O with 128 channels of MADI (AES10), delivering a whopping 188 simultaneous I/O channels — 94 in and 94 out! As the huge channel count was beyond the capability of USB 2, RME employed the novel USB 3 and Thunderbolt computer interfaces for the first time.
Six months later, in 2018, a ‘next generation’ UFX interface appeared — the UFX II — featuring upgraded converters but keeping the original I/O configuration. Indeed, the front and rear panel layouts remained virtually identical to the original UFX.
Introducing The UFX III
Now, five years later, I’m looking at RME’s latest flagship multi‑channel interface, the UFX III. This moniker appears logical enough, but the UFX III is not an updated UFX II. It’s actually a UFX+ Mk2 — because it replicates the massive I/O architecture of the original UFX+ (which it replaces), while updating the analogue and conversion electronics with significantly better THD and SNR figures!
So, like all its UFX forebears, the UFX III has 12 analogue inputs (eight balanced line and four mic/ instrument), plus stereo AES3 and two sets of eight‑channel ADAT — and, like the UFX+, it also has 64 channels of MADI, which my calculator totals to 94 inputs.
The output side is much the same, with 12 analogue outputs (eight balanced line and two stereo headphones), plus AES3, two sets of eight‑channel ADAT, and 64 channels of MADI, making 94 channels again. Thus 188 I/O channels altogether.
For those that like making music for bats, and who don’t need quite as many I/O channels, the UFX III supports sample rates up to 192kHz, but with a correspondingly reduced channel count. As you’d expect, each ADAT interface is limited to four channels at 96kHz and two at 192kHz, while the MADI I/O contracts to 32 and 16 channels, respectively. This means that at double sample rates the UFX III provides 54 channels in and out, while at quad sample rates it’s reduced to 34 channels each way — all still mightily impressive. These counts assume all digital channels (ADAT, MADI, and AES) are synchronised to the same word clock; the UFX III cannot accept asynchronous digital sources.
Given such a vast channel count, computer connectivity is, once more, via USB 3, and to provide the most reliable connections RME has built in sophisticated error detection/analysis, displaying the results in the Settings menu. Any found errors warrant using a different cable and/or computer port, because RME have found these to be at the root of most USB 3 connection issues. In fact, the (superbly comprehensive, 128‑page) manual provides very helpful compatibility information essentially advising the UFX III should only be connected to USB 3 sockets mounted directly on the computer motherboard (and using current chipsets from Intel, AMD, NEC/Renesas, and Fresco), and any remote USB 3 sockets connected to the motherboard via a cable are likely to introduce transmission errors, regardless of the chipset in use. So, you have been warned!
If all else fails, the UFX III also retains an option from the UFX+ which reduces the unit to a 30‑channel USB 2 interface, dropping the MADI channels from the computer interface (although they are still accessible via TotalMix FX for monitoring and external routing).
For anyone who feels 188 channels still aren’t enough, up to three UFX III units (or related Fireface units) can be used simultaneously (provided they are synchronised), appearing as a single combined unit. That said, TotalMix FX controls the DSP within each individual interface, and so channels from different hardware units cannot be shared for monitoring (unless via duplicated connections).
Core UFX Features
Anyone familiar with the earlier Fireface UFX models will feel instantly at home with the new UFX III, which looks and works pretty much identically. The new model confers all the familiar RME features we’ve come to love, including SteadyClock FS for solid, jitter‑free clocking, DURec standalone multitrack recording onto a USB thumb drive (of up to 2TB capacity), dual five‑pin MIDI I/O, Auto‑Set gain controls, DC‑coupled outputs (for passing CV or gate signals to modular synths etc), and class‑compliant interfacing.
The UFX III’s control panel provides options for the buffer size, digital input and output formats, clocking source, and sample rate. Alongside the buffer box is the USB diagnosis report, which shows errors. This image was obtained by plugging into a front (cabled) USB 3 port. Connecting to the rear motherboard port gave zero errors reliably.The latter has some caveats, though: a class‑compliant USB 2 mode (without MADI) is available for all platforms (macOS 10.10 or later, iOS, Linux, and Windows 10‑11), while class‑compliant USB 3 currently works on macOS machines and some iOS configurations.
Although not strictly required for class‑compliant operation, the bespoke USB 3 driver is available for both macOS and Windows and provides access to the interface’s USB settings, such as buffer size, word‑clock input termination, AES and MADI connection formats, AES/MADI/TOSlink output formats, clocking options, and so forth. This driver also installs the TotalMix FX app. For Windows platforms, there’s a dedicated ASIO driver supporting buffer sizes down to 32 samples, which I was able to run reliably on my Windows PC.
For the UFX III the TotalMix FX app provides a powerful 4096‑channel, 46‑bit mixing engine with EQ, dynamics and effects capabilities for comprehensive monitoring and external signal routing. As usual, TotalMix FX can also be controlled remotely via MIDI or through an OSC setup, as well as via the TotalMix Remote app. This can be installed on any PC, Mac or iPad connected to the same network as the host computer (via Ethernet or WiFi), greatly expanding the system’s versatility and allowing user control away from the host computer.
RME’s optional ARC USB remote panel can also be used to control the UFX III, either via a USB socket at the unit’s rear, or via any USB port on the host computer, and the ever‑useful DIGICheck Analyser app is also available, of course. This provides comprehensive level metering in multiple formats including sample peak, RMS, true peak, BS1770 Loudness, and K‑system. A correlation (phase) meter, stereo and surround vectorscopes, bit statistics, channel status and spectral analysis are also included, all driven from the UFX’s DSP.
Hardware
As with previous incarnations, the UFX III is housed in an elegant 1U rackmount chassis but, while it outwardly appears the same as its predecessors, the innards have been completely redesigned, with new converters and mic preamps that are essentially the same as those used in the outstanding 12Mic.
Four combi XLRs on the front panel accept mic or instrument inputs, and a pair of quarter‑inch TRS sockets provide two independent headphone outputs (but can also be used as unbalanced line or CV/gate outputs). Next along are a pair of five‑pin MIDI in/out sockets, and then a USB 2 Type‑A port for DURec recording to a thumb drive (which supports track naming, as in the UCX II). The remaining right‑hand third of the panel is the control section, with a small colour screen which shows I/O meters when not used for configuration. The menu operation is identical to the UFX II interface, and similar to that employed on the UCX II and the ADI series, so will be plain sailing to most RME users. Status LEDs provide clocking information on the left column and MIDI monitoring on the right and, as in the UCX II, the front‑panel controls can be remapped to suit specific standalone operations as well as locked to prevent accidental operation, if required.
Round the back things are pretty busy, but not as busy as you might think with so much potential I/O.
The rear panel is equally familiar, starting with octets of balanced line inputs and outputs on TRS sockets — except outputs 1+2 which are on XLRs. AES3 in/out are also connected via XLRs, while two sets of ADAT TOSlink ports are provided, with both sets being reconfigurable as optical S/PDIF if required, making three AES or S/PDIF channels available.
A pair of BNC connectors provides word‑clock in/out by default but can be repurposed as a coaxial MADI I/O, if necessary, although the primary MADI interface is on standard SC fibre‑optic ports. Having both fibre and coaxial MADI options allows for redundant connections, and the UFX III switches automatically (in less than a sample) between the MADI optical and BNC inputs if the active source is lost. MADI outputs can also be mirrored to both the optical and BNC connections, for redundancy again, if required.
Supplementing the front‑panel MIDI I/O is a second set of five‑pin MIDI in/out sockets at the rear and, like other RME units, MIDI data can also be sent and received via the MADI connections. The UFX III has an internal (Class 1, grounded) universal power supply accepting any voltage between 100‑240 V AC through a standard IEC inlet (consuming between 19 and 25 Watts). The host computer is connected via a ‘double‑decker’ USB 3 Type‑B socket, and both USB 3/USB‑C and USB 3/USB‑A cables are provided in the box (along with a mains cable and ADAT light‑pipe fibre). Finally, a USB 2 Type‑A socket accepts the optional ARC USB remote controller.
Delving into the analogue I/O technicalities for a moment, alignment options are similar to other RME units, with inputs being switchable to achieve 0dBFS at either +13dBu or +19dBu (equivalent to the +4 and Lo Gain modes in legacy RME interfaces). On the output side, 0dBFS generates either +19dBu, +13dBu, or +2dBV (+4dBu) at the TRS outputs, while the XLR outputs (channels 1+2) have a fourth option delivering +24dBu.
It won’t bother most potential UFX III users, but it’s a shame that the UFX III doesn’t support +24dBu peak level on all its line I/O — especially when other recent RME interfaces do — as it potentially complicates connecting the UFX III with professional mixing consoles and outboard equipment working with 20dB of headroom.
Headphone outputs on the front panel use the same D‑A converters as the balanced line outputs and can be switched between High (+19dBu) and Lo (+4dBu) operating levels in a similar way. However, their output stages are optimised to drive low‑impedance loads, delivering maximum power (200mW) into 32Ω headphones. All 12 analogue outputs are DC‑coupled, avoiding LF phase shifts for audio signals, and allowing the generation of DC control signals (CV and gates) for synthesizer modules or for scientific measuring equipment. When set to the High output mode, a maximum DC voltage of +9.5V can be generated, reducing to +4.75 for the +13dBu setting, and +1.7V for the Lo (+2dBV) mode.
The four microphone preamps (channels 9‑12) offer a gain range of +8 to +75 dB in 1dB increments, plus a unity gain (0dB) setting allowing the XLR to accept line inputs (up to +18dBu). The preamp’s EIN figure is a very impressive ‑129.8dBu (60dB gain, 150Ω source, A‑weighted) — meaning these are very quiet preamps! If selected, the AutoSet feature optimises the preamp gain automatically to preserve 6dB of headroom.
Phantom power is available on the XLRs, of course, but doesn’t reach the combi‑jack instrument connections, which are presented with the usual 1MΩ input impedance. For instrument inputs the preamp’s maximum gain is reduced to +50dB and can deliver 0dBFS for any signal level between ‑21 and +21dBu. As you’d expect, the technical specifications for all inputs is exemplary, with the very worst THD figure being 0.00045 percent and the best 0.0001 percent! My own Audio Precision bench‑test gave AES17 dynamic range figures of 119.1dB (A‑weighted) for both the A‑D and D‑A converters — which is hugely impressive.
In my personal league table of measured converters, the UFX III’s D‑A performance places it between the Focusrite RedNet or Crookwood M1 mastering console and the Grace Design m905 or Lynx HiLo. And the A‑D performance lies between Prism Sound’s Dream ADA128 and Cranborne’s R500 — so this is a genuinely top‑notch, mastering‑grade interface!
I couldn’t fault the UFX III in any way and it’s impossible not to be impressed with RME’s latest offering.
Bottom Line
For readers who habitually skip to the end of a review, the bottom line is that the new UFX III is much the same as the old UFX+, but with seriously impressive converters and a quartet of stunningly clean and noise‑free mic preamps — plus all the wealth of connectivity and features we’ve come to associate with the UFX marque. The new TotalMix Remote app will be a boon to many, too. I couldn’t fault the UFX III in any way and it’s impossible not to be impressed with RME’s latest offering, which clearly deserves its flagship title.
Pros
- Superb converter and preamp performance.
- Immense connectivity in a familiar package.
- Triple AES and S/PDIF option.
- DURec now supports track naming.
- Integrated USB 3 error checking.
- Fully deserving of RME flagship status.
Cons
- None.
Summary
The latest incarnation of the UFX platform boasts a stunning technical performance with vast I/O, familiar RME operation and features, and reliable USB 3 connectivity.
