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This review first appeared in the January 2014 issue of hi-end hifi magazine of Germany. You can also read this review of Nubert
in its original German version. We publish its English translation in a mutual syndication arrangement with the publishers. As is customary for our own reviews, the writer's signature at review's end shows an e-mail address should you have questions or wish to send feedback. All images contained in this review are the property of fairaudio or AURALiC or Audeze- Ed.

Reviewer: Jörg Dames
Sources: Laptop w. foobar2000, JRiver MC + Phonosophie DAC1 Fonel Simplicité
Amplification: Fonel Emotion and Abacus Ampino integrateds; Funk MTX Monitor V3b + Audionet AMP monos pre/power
Loudspeakers: Quadral Aurum Megan VIII, Spendor SP100R², Thiel CS3.7
Cables: low-level - Straight Wire Virtuoso, high-level - HMS Fortissimo, Reson LSC 350
Power delivery: Quantum Powerchords, Hifi-Tuning Powercord Gold w. IeGo plugs, MF-Electronic power bar
USB: Wireworld Starlight, Chord USB SilverPlus
Rack: Lovan Classic II
Review component retail: €1'050/pr

"Man, when I listen to my earlier stuff, what crap I built then!" This was a speaker designer's admission during a casual chat. But 'admission' overstates the negative connotation. His older models were far from poor. Quite the contrary I think. He also didn't mean to undercut his own competence. His flippant utterance rather pointed at how advances in driver design, computer-aided simulation and measurement gear have improved the entire sector. Of course the learning curves of designers must point up too. Over the past 5-10 years much has happened which is overlooked by those who focus solely on soulless product pumped out by more or less anonymous big corporations. Stand-out performers have always existed. But it's fair to say that the entire mid-level sector has been upwardly mobile on sound quality particularly at the affordable end. Once we look closer, the constantly revising/revisiting R&D-obsessed folks at Nubert check in. It's astonishing just how mature and 'correct' even their 3-digit priced solutions can play.

Freshly minted, Nubert's nuPro A-300 just crosses the €1'000 barrier. This nets a pair of boxes which moves air, amplifies, converts digital and controls signal strength by remote. And no, that doesn't make it a typical desktop denizen. Already the 37 x 22.5 x 27.5cm HxWxD dimensions demur. As we'll see, so does the sound. I'd characterize this model more as a complete system. There are four inputs: coax, Toslink and USB for digital, RCA for analog. There's even a subwoofer output. Source switching and volume are by credit-card remote. Just add a laptop/PC with decent media player like Jriver/Foobar; or a CD player or other source. Time for tunes already.

Each box packs 2 x 100 watts to drive tweeter and mid/bass driver with dedicated digital amps. Whilst power ratings are also used to impress punters, more important in the end tends to be the 'how' of the circuitry. And here that's interesting because Nubert talk digital amplification. We of course know that class D doesn't mean class digital. Most such amps with digital inputs follow their DSP front ends with D/A conversion which can then be processed class A, class A/B or with an analog switching output stage aka class D. With that in mind I asked Markus Pedal, key developer in the nuPro range, what distinguishes their so-called digital amps.

"As you know, class D generates a PWM signal by comparing the analog signal to a triangle wave. The result is a signal with two amplitude states at variable pulse width. It's neither fully digital nor analog but a type of hybrid which shouldn't be called a digital amplifier. In our nuPro models there's no D/A conversion after the DSP stage which mathematically converts incoming PCM data to PWM which now switches the output transistors directly. Unlike conventional class D this is purely digital [hence NAD and NuForce refer to their equivalents as direct-digital amplification – Ed]. The elimination of a D/A stage creates astonishing S/N ratio particularly when the digital inputs are used to avoid conversion losses." To reiterate, the most direct input path is via digital since the analog input relies on conversion to digital by Cirrus Logic CS5364. Whether that implies sonic penalties we'll get to. Conversion of the digital inputs to finally analog sound from the speakers only involves a low-pass filter between the direct-digital amp modules and drivers. Both S/PDIF ports (coax and Toslink) process 24/96 data whilst the synchronous USB input is limited to 16/48, making it good for both Redbook and DVD. Hi-rez computer music won't work without prior down-conversion in a media player. I wasn't bothered. My library is dominated by 'normal' CD quality. I reckon that's true for most readers.