For the dedicated audiophile, the RME ADI-2 DAC provides an excellent combination of superior sound quality, extensive functionality, and affordability. It’s a streamlined version of RME’s ADI-2 Pro AD/DA converter that’s found in many of the world’s finest recording studios.
Professional-quality DA conversion, exceptional headphone and in-ear monitor (IEM) outputs, a powerful EQ section, and an extended remote control have helped the ADI-2 earn numerous enthusiastic reviews.
OK, that all sounds great, but if you’re new to the world of high-end audio, you might be wondering what a DAC is, why you might need one at all, and why the ADI-2 could be a good choice for you.
So, let’s examine each of these questions in more detail in our RME ADI-2 DAC Review…
What’s a DAC?
“DAC” is an acronym for “Digital to Analog Converter.” A DAC is either a discrete device or a collection of electronic components on a circuit board. It changes the digital audio output signal from your smartphone, tablet, computer, or digital audio player – basically a stream of numbers – into an analog signal that can be amplified and heard.
In most consumer gear, the built-in DAC is simple. And is just a single integrated circuit (IC) “chip” plus a few associated components. On the other hand, serious audiophiles sometimes spend tens of thousands of dollars for a standalone DAC unit in order to get what they believe to be the most accurate music reproduction possible.
Do You Really Need a Standalone DAC?
The first standalone DACs were introduced in the 1980s. This was because many of the early consumer CD players included poor-quality converters. Listeners with high-end headphones and speakers could often hear the acoustic artifacts these devices added to the music. And so numerous companies sprang up to fill the void, producing professional-quality discrete DACs.
Today, the converters used in most audio equipment are of much higher quality, so the need for a standalone DAC is less urgent. However, they’re still better than what you’ll find in your phone, computer, or portable music player, and that difference is audible. So if you’re a critical listener who values accurate music reproduction, a dedicated DAC is worth serious consideration.
Also, most DACs provide a variety of additional useful features, which we’ll describe below. Ultimately, you have to balance the improved sound and extra functionality against the often significant cost of a quality unit.
The ADI-2: Looking Under The Hood
Physically, the ADI-2 DAC is a half-rack unit, relatively small compared to many audiophile models. Without optional rack ears attached, it measures just 8.6 x 1.73 x 6.1 inches (218 x 44 x 155 mm) and weighs 2.2 pounds (1 kg). The metal chassis is very solidly built. An included remote control is quite handy, though its plastic case feels less robust by comparison.
Ins & Outs
The ADI-2 DAC provides reference-class conversion from SPDIF coaxial, ADAT-compatible SPDIF optical, and USB 2.0 inputs. Outputs include balanced and unbalanced analog, a headphone output with an Extreme Power (+22 dBu) option, and a super low-noise in-ear monitor (IEM) output. The SPDIF input signal can be directly recorded via USB.
The headphone and IEM output jacks are located on the front panel. The 1/4-inch stereo headphone jack is not a balanced output, but with a signal to noise ratio of 119 dbA, it can be used as a line output. This “Extreme Power” output is rated at 0.1-ohm impedance and provides enough power to drive any headphones.
Also, a mute relay is activated one-half second after the headphone is inserted, then the DSP ramps up the volume slowly to the last used state.
The IEM output uses a 1/8-inch mini TRS jack. It’s extremely quiet, a remarkable 10 dB lower than the headphone output. The output impedance is close to zero ohms, and both click-free on/off and volume ramp-up are included.
Most of the connections to the ADI-2 are on the back panel. Both RCA inputs, for SPDIF and AES/EBU, and ADAT TOSLINK optical inputs are provided. Both inputs support all sample rates between 32 and 768 kHz. A TOSLINK cable is optional and not included. Also on the back are balanced line outputs with dual XLR connectors and unbalanced RCA outputs.
A locking power jack accepts any 8V – 28V DC, or 8V – 20V AC adapter. The included adapter is a regulated switching 12V DC power supply that works with any line voltage from 100 to 240 VAC.
Front Panel Functions
On the far left is the on/off touch switch, with an LED ring to show when the unit is on. To the right are the headphone and IEM jacks, and a large, LED-lit volume knob to set the headphone output level.
The most prominent feature on the front plate is the main control panel. It comprises a large two-section color LCD screen plus an array of push buttons. By default, the larger screen shows the ADI-2’s output and volume, the file sample rate, and a 15-band spectral analyzer.
When changing operating parameters, it displayed the various options. The smaller display section below is a six-segment stereo level meter that also shows the last recent peak.
The control panel includes four square buttons that allow you to make volume adjustments, select the input source and output destination, adjust tone settings, and make other setup changes. This includes selecting among five different DAC filters: Short Delay Sharp, Short Delay Slow, Sharp, Slow, and NOS (No Oversampling).
And on the far right are two large buttons for selecting different parameter settings.
An attractive feature of the ADI-2 is its AutoDark mode. This option turns off the display after ten seconds, including function keys, volume knob, and standby button. Touching any button or control turns the lights back on for ten seconds, and using the remote control turns on the display for three seconds.
Masters of Tone
ADI-2 gives you unprecedented control over the sound you hear through headphones. Of course, it provides the familiar Bass and Treble controls, but they come with adjustable gain, frequency, and Q.
There’s also a Loudness adjustment. This legacy feature from classic hi-fi gear provides a bass and high treble boost to compensate for perceived acoustic changes when listening at low volume levels. The ADI-2 Loudness control is much more versatile than the older designs, allowing separate adjustment of treble and bass boost.
But the star of the ADI-2 tone control section is its five-band parametric equalizer. Each of the five filter bands has an adjustable frequency from 20 Hz to 20 kHz and adjustable Q of 0.5 to 9.9. Bands 2 – 4 are peak filters, while bands 1 and 5 can be set to peak, shelf, high cut, or high pass mode, with a slope of 12 dB/octave.
ADI-2 includes a Crossfeed adjustment that reduces the artificially extreme surround ambiance added to some recordings to make them sound better on speakers but unnatural on headphones. An advanced algorithm (known as the Bauer Binaural method) adds some frequency-specific delay and volume correction, with five selectable settings.
To help get a better idea of what frequencies might need tweaking, the ADI-2 includes a 15-band spectral analyzer, covering the range of human hearing from 20 Hz to 20 kHz. It uses 29 bandpass filters to provide maximum separation between bands for more accurate visualization. It’s easy to see even from a distance.
The ADI-2 DAC includes a well-designed remote control. Clearly labeled back-lit buttons make it readable in low light. There are buttons for power on/off, input source selection, volume, left/right balance, tone, and loudness on/off and muting. As a bonus, four programmable buttons can be assigned to any of 22 commands.
At the heart of every DAC is the converter itself. The ADI-2 provides extremely accurate 32-bit conversion at all standard sample rates from 32 kHz to 768 kHz, with a signal to noise ratio of 120 dB. It’s designed around the Asahi Kasei Microdevices 4490 IC, a premium DAC that uses AKM’s “Velvet Sound” architecture.
Sampling accuracy is ensured by RME’s SteadyClock technology. Thanks to a quartz-controlled phase-locked loop (PLL) design, SteadyClock is virtually free of jitter, typically accurate to a picosecond – a trillionth of a second. This eliminates any audio artifacts that might otherwise occur from an uneven rate.
These are all great features, but how does it sound?
As a digital to analog converter, and a preamp for an external power amp, the ADI-2 is completely transparent, not adding any color or audible noise to the signal. The volume control increases the level in 0.5 dB increments, so it sounds very smooth with no “stair step” effect. The channel balance sounds perfect.
The ADI-2’s parametric equalizer sounds like a good analog EQ. It’s effective at making subtle tweaks to material that might not have been perfectly mastered, or adjusting for room acoustics. And the Bass, Treble, and Loudness controls are extremely versatile, adding just the amount of emphasis you want.
The converter’s AKM 4490 IC includes five different digital filters, to let you try out different possibilities for the best sound. Most users prefer the sound of the Sharp or Slow filters.
The headphone output sounds fine, with enough power to drive any model. And it’s quiet enough to be used as a line output in a studio or home listening environment. However, a few more fanatic audiophiles, perhaps concerned by the ADI-2’s relatively modest price, prefer using a dedicated headphone amp. The ultra-quiet IEM output is amazing.
Sonically, it’s hard to find fault with the ADI-2, although there may be better (and more expensive) discrete headphone preamps. It would be nice to have a newer USB-C connector and 3.0, and/or a Thunderbolt interface, to make it more convenient with a PC.
RME ADI-2 DAC Pros & Cons
- Incredible technical performance.
- Stylish all-black design.
- Advanced DSP functions.
- Elegant configuration and control options.
- Dedicated IEM output.
- Useful AutoDark mode.
- Can route digital sources over USB.
You May Also Need Some Headphones?
Looking for a pair of headphones to go with your new DAC? If so, check out our reviews of the Best Sony Headphones, the Best Studio Headphones for Home Recording, the Best Headphones for Rock Metal Music, and the Most Comfortable Headphones currently available.
RME is a renowned German company with a long history of developing high-end audio solutions, including audio interfaces, converters, and preamps.
Their products are often found in professional and project studios worldwide. So you can buy their products knowing they have a long-term commitment to the audio industry, and the financial resources to continually update and improve their product line.
Reviewers in audiophile publications often engage in “cork-sniffing,” comparing the ADI-2 against other DAC units that cost orders of magnitude more. Some of their technical claims might be true, though whether any of these differences are really audible is a different question.
But at the end of the day, the RME ADI-2 may very well be the best overall DAC you can buy in its price class. It has almost every feature you’re likely to need (the few exceptions noted above notwithstanding). The user interface is well-designed and easy to understand.
Coupled with a premium power amplifier and speakers, the ADI-2 can form the center of a powerful music system. Its many happy owners are proof of this.