Review NAD D 3020 Hybrid Digital Amplifier

In 1978 NAD introduced the revolutionary 3020 integrated amplifier, one of the more famous and commercially successful amps ever. High End Munich 2013 marked NADs 40th birthday and saw the introduction of its modern descendant: the D 3020 hybrid digital amplifier.

HiFi.nl is proud to be the first to review this new generation amp, which is why we chose to present our findings in English as well (Our Dutch readers can find the original review here). So without further ado, here's what we thought of NADs youngest, a digital amp that showed us a thing or two that was thought impossible from a 500 dollar piece of equipment.

Review: Eric van Spelde
Translation: HiFi.nl 

It appears to be a prime example of how not to compose a hi-fi audio set: a high quality digital source, a turntable combination with a top notch MC-element that channels its signal through a good step-up transformer and an amped-up tube phono preamp, a couple of horn loudspeakers in the price range of a full options mid-sized sedan, and in between the crucial amplification element that is… What exactly? A tiny desktop amp that measures approximately 2.5 by 7.5 by 8.5 inches, weighing roughly 4 lbs. But: it sounds awesome nonetheless. The tiny NAD D 3020 beats hifi laws as it goes, just as its illustrious predecessor (no “D”, but with a phono preamp) did in 1978.

What exactly is the D 3020? Its manufacturer calls it a “hybrid digital amplifier”, hybrid meaning that it is not a fully digital amp that converts an analog input signal into ones and zeroes, or that all the normal functions of a preamplifier are in the digital domain, as they are with digital NAD or Devialet amps in higher price ranges. Rather it's a combination of a D/A-converter with a Class D output stage, a design by Dutch electronics company Hypex. The output stages are discreet and – according to the manufacturer – completely insensitive to changes in loudspeaker impedance. Put differently, the sound doesn’t follow changes in the loudspeaker impedance, and the amplifier has no fear of very low impedances.

The output impedance is also low as well as evenly divided over the entire frequency range. The supply circuit features the latest evolution in NAD's PowerDrive, a circuit that controls the output voltage by its actual load. PowerDrive can deliver high voltage levels for short power peaks, without kicking the device into (thermic) safety mode. NAD therefore claims that despite the low output levels of 2 x 30 Watt, the D 3020 has the potential to control “difficult” loudspeakers with relative ease.

En route to the end stage, NAD uses a 24bit/196KHz eight channel D/A-converter that mixes its output to two channels. This should result in a higher resolution. Digital inputs aplenty: D 3020 counts one USB, one coaxial and two optical connectors, plus an option to wirelessly stream from a smartphone or tablet using Bluetooth. The USB port operates in asynchronous mode: driver software for computers and laptops is available for download from the NAD website and can be put to work to minimize inevitable jitter that generally comes along on these platforms, unless they are properly configured for hi-fi purposes by someone who knows what he’s doing. Finally, and thankfully for people like myself, the little amp also has one analog output on board.

Armed with the general tech specs as laid out above, curiosity starts to develop towards what this gadget-sized, lightweight device, that seems to taunt the laws of hi-fi physics for amplifiers in both size and design, has to offer to the ear in the musical sense. What, no big toroidal transformers? A switched-mode power supply, really? No special damping feet? And a Mickey Mouse net entry instead of a solig IEC-connector, or even a shaver plug? Nothing gilded or gold-plated? Nah, this can’t be good…

Music

Because the device is light enough to carry around, we first take it to an environment in which it should be able to stand tall. A Marantz DV-6200 DVD player’s audio channel is easily connected to the D 3020 through the coaxial digital output (and thus acts solely as a drive mechanism). The speaker terminals are hooked up with a pair of Dali Ikon 5 Mk2 speakers. They provide a fairly flat impedance curve at a relatively mediocre efficiency (87 dB/W/m, as specified by the manufacturer) and while they always perform nicely with any amp, they do appreciate a partner that stands tall when it comes to power supply.

Between unboxing and “power on”, it’s love at first sight. The magic device brings life, color and body in music playback in a way we really quoie haven’t heard before, not even in combination with amplifiers that stand higher up on the store shelves. Bass is tight and deep, voices and instruments sound more tangible, and everything pieces together effortlessly. The DAC and its amplifier stages bring out the finer qualities in the Dali speaker set while at the same time adding a full-blooded, dynamical character to the rendition that makes you forget you are listening to relatively small standing speakers. All things considered, it’s pretty impressive.

Strengthened (or overconfident?) by this experience, the device is being set up with two Avantgarde Duo loudspeakers, connected through a 47Labs 4708 OTA cable. The Duos have an upgraded crossover, with Sprague paper-in-oil capacitors with a Teflon bypass and Tritec air coils. The CEC CD drive passes its digital output signal through the Audio Note AN-V coaxial cable not through an Audio Note DAC 3.1x with De Jong Systems upgrade, but is directly linked to the D 3020. Connected to the analog input is a phono-chain, that appears to be just an unbalanced a choice in terms of ratio between price of the various components, as the ratio between the amplifier and the speakers is.

(Enlarged? Click the image!)

A wildly expensive but very good Brinkmann EMT Titanium phono cartridge is built into the tone arm of a Music Hall MMF 9.1 turntable. The step-up transformer is an older model by Audio Innovations, and the phono stage is a heavily modified Audio Note M1 RIAA with, among others, a choke-loaded power supply. This really can’t work, can it? An element at almost one and a half times the price of the turntable plus tone arm, a CD drive in the top range, and a “desktop amplifier” with an onboard DAC priced just under 500 dollars, connected to a set of loudspeakers thirty times the price...

Well. It actually does work. In spades. One listener observed that not for a moment he felt that he was listening to a makeshift collection of audio components, that’s how convincing the overall performance was. The ability of the Avantgarde loudspeakers to blend intimacy and engagement with an almost unprecedented magnitude, directness and dynamics, remained fully intact and stood tall. Record after record, cd after cd is thrown at the D 3020 to test its abilities. In between we fool around with different interconnects and net cables, resulting in audible differences. Most strikingly, the output sound is completely free of the sonic artifacts that usually betray conventional class AB amplifiers (both transistor and valve amps) in a comparable setup. The D 3020 keeps its act up in the same way a much pricier D class design would. This quality is probably attributable to the basic design with short signal paths, which makes the music playback sound direct, natural, clean and fast.

The Verdict

It appears that over the past couple of years Class D technology has made a few leaps that wedged it into a position from where it could seriously undermine the existence of conventional amplifier circuits. In my own setup, only single-ended, non-feedback amps (with tubes, J-FETs or whatever) would be able to step up to the same level of dynamic and timbral contrasts, the “body” and expression of voices and instruments in the middle ranges, and the reproduction of “small” signals that really bring a recording to life. But those amps would have a lot of difficulty convincing the loudspeakers connected to it to dance to its tunes –at the ends of the frequency spectrum you would have to give in.

Does this mean that we should simply disregard all high-end amps from now on, and put D 3020s in their place to steer sounds to any top range set of loudspeakers? Nah, that would cut a few corners too many. The Avantgardes with their high efficiency, simple crossovers (only a second-order filter for high frequencies, that’s it), and active bass modules, obviously form an exceptional pair with the D 3020. Reportedly, the D 3020 is adequately equipped to work with – let’s say – a pair of Dali loudspeakers from the Epicon series, but then the audible differences when compared to an M2 (same brand, ten times the price) are clear-cut. But still…

In my setup, the D 3020 showed a thing or two that was thought impossible for a 500 dollar piece of equipment. It performed way above the average level associated with its price range. It makes you wonder what more possible combinations are left open for this little amp, what other setups would allow it to make optimal use of the ingeniously simple and direct technical layout of the device. Maybe a pair of good wide-rangers, or derivative designs (e.g. Zu Audio), could do some good. Or perhaps a fast two-way system, with minimal but well-designed cross-overs. But the Dali Ikons, who fall in none of the aforementioned categories, rose above themselves in some respects when supplied with input from the D 3020.

The D 3020 and its brothers in Munich, High End 2013

Obviously, the rather common combination of Dali with NAD is not exactly an “startling discovery”, but in this price range I never experienced a musical performance of the two together at these levels, which leads to believe that further experiments could really pay off. Don’t just assume that a pair of 300 dollar speakers bring out the best in the D 3020. You might falsely conclude that the next phase in your setup should then be to replace your amp. Instead, try to do it the other way around, and acquire those second-hand speakers you always dreamed of having, but were financially out of reach. You may well be pleasantly surprised. Just like its illustrious predecessor, this lovely, small, almost lifestyle-like NAD-device has the potential to do away with a lot of widely accepted hi-fi laws. I’m really looking forward to see how the D 3020 is going to do in the market...

HiFi.nl Pro’s & Con’s:
+ Compact, fits anywhere design
+ Wireless Bluetooth streaming
+ Coaxial, optical, and USB inputs
+ Handles a wide variety of speakers, including “difficult” models
+ Musical qualities that far exceed its price!

- Only one analogue input (but what can you expect in this price range?)
- Operation (touch sensitive surfaces, volume control) takes some getting used to (but the remote, on the other hand, is easy to use)