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Unlike Zanden's Yamada-San who prefers yesteryear's technologies exclusively (tubes and 1985 vintage chips), Audio Aero takes full advantage of the most sophisticated latter-day processing engines, then weds them shotgun-style to direct-soldered miniature tubes. Before you actually listen to it, Yamada-San's DAC could be conceptually disqualified as a strange throwback into retro. Audio Aero's cannot. Those computational Swiss super chips won't let you. This begs a question. Why valves in digital low-level circuits? Aren't such circuits based on tolerances, radically low noise floors and minuscule distortion figures which tube makers decades ago couldn't even conceive of? Don't valves in digital circuits then equate to spoked wooden chuck wagon or buggy wheels on a modern turbo ride?

Some audiophiles -- and designers I'd wager -- would likely put it in exactly such terms. And it's certainly true that all manner of digital antidotes (one actually called that), mysterious black-box interfaces, tubed interconnects and sundry add-ons all did make short-lived appearances during the early days of digital. When digital eventually separated into multiple boxes, then unified again with outboard DACs falling out of vogue, universal machines picked up the slack. They now ran in parallel to the upsampling craze of surviving traditional RedBook playbackers. It's only been in the last few years that tubes have joined the digital bandwagon, mated to advanced silicon that sports outrageous performance specs and parallel processing speeds far more typical of IT, telecommunications and military applications than consumer audio.

So what gives? If audible satisfaction were tied to super-human math specs, tubes especially in digital should be bad medicine. Call 'em cockroaches from a prior cycle of evolution that stubbornly refuse to die out. In fact, call 'em back with a bloody vengeance. Some of the tweakiest ears in the biz stick 'em into testbench-perfect Sony and Denon universal machines. Generally speaking, tubes excel with decays, transistors with transients. Generally speaking, tubes are even-order gals, transistors are odd-order guys. Both have detractors and admirers (and Nelson Pass deliberately designs amps for either camp - with transistors only to prove that every rule can be broken). Generally speaking, tubes are more dimensional, transistors drier. And so on.

As far as I'm concerned, the most attractive strengths of tubes are spatial staging/layering and more expansive microdynamics followed by various degrees of tone. Last but not least, the high-frequency performance of tubes is often more suave and elegant. On the downside, there are liabilities like undue thickness, a loss of speed and attack, a lack of drive and LF control and aberrations due to output impedance modulating the loudspeaker's frequency response. The latter is obviously a mute point with digital. It never interfaces directly with a speaker. For the same reasons, drive, control and bass issues don't bother digital (and technically speaking, it isn't in the digital side of DACs or CD players but in their analog output stages where tubes are employed.) On the liability ledger of tubes in digital, this only leaves disproportional density i.e. THD fog. Also, let's consider a potential shift away from leading edges into the subsequent bloom and fade of tones which could undermine rhythmic energy if out of control.

Still theoretically speaking, doesn't some of this sound like the perfect antidote to digital edginess, thinness, compacting of dimensionality and grainy treble? Perhaps digital in fact is the perfect place to use tubes. You can fix certain issues at the source rather than farther downstream while sidestepping the whole damping factor, output impedance, drive and control issues. You also avoid hard duty with its high voltages and the potential (catastrophic) failures thereof. The primary challenge of using valves in low-level circuits then, right at the beginning of the chain, deals with microphonics i.e. noise issues. After all, there's little sense in selecting laser-trimmed hi-tolerance chips with blinding speeds and stunning S/N ratios only to weigh them down with the dither of tube noise. If ever there was a textbook example for how to mate 21st-century DSP sorcery with the best of valves while banishing the latter's weaknesses into never-never land, the Audio Aero Prima is it. Part of the reason could be the use of military-type subminiature tubes. Those were designed to higher specs than consumer (audio) applications to begin with.

With the Audio Aero Prima, you get the good without the bad and the ugly (Saludos to Ennio Morricone, Sergio Leone and Clint Eastwood). You get the apparent transparency and detail retrieval of Ensemble's DVD-upsampled separates without their relative dryness. You get just a smidgen of voluptuousness but no weight issues, no excessive lushness nor the notable warmth and minor darkness of the Einstein CDP. Whatever noise issues the books tell us to expect seem to have their ass in a sling. So much for generalities. Casual listening immediately suggests dynamic fortitude, image heft and a complete absence of chalkiness, nervousness, hype and pushiness. Yet nothing sounds slower than it should nor do percussive attacks seem blunted or unduly softened. Rather, everything appears to be exceptionally well balanced. It's finesse and elegance painting with the delicacy of a single-hair brush. If there were tube-induced compromises, they didn't telegraph and would require very serious listening to tease out. In which case, "compromise" really would be the wrong term to describe what the Prima DAC does.

Clearly, the Prima is not a sterile by-the-numbers affairs. Unlike machines specifically designed for pro use where a recording engineer needs to make surgical decisions at his mixing console, the Audio Aero is deliberately designed for listeners who crave involvement. This, as I've begun to investigate in my recent 3-preamp review, can mean additive behavior or subtle enhancements when compared to a DAC like the Benchmark which is more matter-of-fact.

Stay tuned for the head-to-head comparisons of the Audio Aero Prima to my Zanden DAC and the Benchmark DAC. The still in-house Overkill Audio review rig with its 4-channel DAC requirements delays this conclusion until I can return to my customary reference system.
The new cosmetics of the Prima CDP, DAC and amplifier