Micromega AS-400 D/A integrated amplifier

Blind though I am to the allure of blind testing, I can appreciate some degree of review-sample anonymity: Distinctive products elicit distinctive responses, but a plain black box encourages us to leave our prejudices at the door. It asks of us a certain . . . objectivity.

So it was with the Micromega AS-400 digital source/integrated amplifier ($4495), the anonymity of which was compounded, in my case, by a generous helping of forgetfulness: I suppose I was told, ahead of time, that this was a class-D amplifier, but at some point in time before my first at-home audition I apparently killed the brain cells responsible for remembering that fact. So I was innocent of conscious prejudice when I listened to this elegant cipher of a box and wrote, in my notes: "Dynamic, dramatic, and almost relentlessly exciting with some recordings. Imbued pianos with almost too much dynamism for the room—too much being very good!—but lacked some 'purr' in the die-away. Basically fine and fun. Wish it had a little more color and spatial depth."

All enduringly true. And you could stop there if you wanted. But the thing is, there's a lot more to the Micromega AS-400 than just that.

Rather like the Linn Majik DS-I before it, the Micromega AS-400 combines a solid-state preamplifier and power amplifier with a custom digital-to-analog converter, the latter tailored specifically to computer-music files (more on that in a moment). Also like the Linn, the AS-400 comes complete with its own phono preamp: a lovely trend, and one that would seem to allow the buyer to take advantage of both the new and the old in terms of cutting-edge music media.

Yet one could argue that the AS-400's real calling card is its implementation of something that Micromega calls their AirStream module—essentially, an Apple AirPort Express WiFi receiver that has been reworked as a perfectionist audio component. Micromega uses three different feeds from an R-core transformer to supply its main module, master clock, and D/A analog section. The incoming digital stream is referenced to the AirStream's own custom-made timing clock, then fed to a 24-bit/192kHz Cirrus Logic CS4351 chip, supported with various perfectionist-quality parts. (The D/A in the AirPort Express is not used.) First seen in Micromega's WM-10 standalone digital source, the AirStream module is intended to allow the owner of an AirPort-equipped Apple Mac or similar computer to wirelessly stream his or her iTunes music files to a perfectionist playback system, thus making an end-run around the whole USB thing.

Not only is the AirStream module in this new product said to be more advanced than those in Micromega's past, but computer-music technology in general has progressed in such a way that a new frontier is available to the prospective AS-400 owner: At the end of 2010, Apple released v.4.3 of their iPod operating system, which incorporates a new wireless-transmission protocol called AirPlay (footnote 1). The long and short of it: One can now wirelessly stream full-resolution 16-bit/44.1kHz, iTunes-compatible music files from an iPod to a Micromega AS-400. Compare that with the Chordette Gem D/A converter (reviewed in the January 2011 issue), which uses Bluetooth wireless technology and a necessarily lossy codec to accomplish the same thing.

The Micromega's phono section deserves special mention: Its sensitivity is appropriate for moving-magnet cartridges, but moving-coil types will require additional gain (and, for most users, a load impedance considerably lower than the AS-400's MM-appropriate 47k ohms). For me, that's no hindrance, as I far prefer loading my MC cartridges with an outboard step-up transformer. Additionally, Micromega has engineered the AS-400 so that, when its phono inputs are selected, power to the AirStream module is interrupted, so that the latter's own power-supply feeds won't add noise to the delicate phono signal. Nice.

Finally, no discussion of the Micromega AS-400 would be complete without mentioning its amplifier output section, which is class-D—perhaps the most misunderstood of the classes, second only to the working poor. The D doesn't stand for digital—although there is, coincidentally, a digital-like concept behind this 60-year-old design: Its output devices are always switched either on or off. The resultant wave is shaped via pulse-width modulation (which is not nearly as digital as it sounds) in an effort to mimic the original signal.

All of the above is housed in a metal enclosure of average proportions and with an above-average level of finish. Perfect is not too strong a word to describe the fit of the casework, the powder-coat finish is uncannily smooth, and the front panel is the very model of understated elegance. Above all other adjectives, the AS-400 looks mature.

Setup and installation
When I open the carton of a new review sample and see that it contains a software disc, the first words out of my mouth are usually "Oh, shit." The Micromega came packaged with a set of discs, but I needn't have panicked: It turned out to be the software and documentation Apple supplies with every AirPort Express they sell; chances are, the AS-400 user will never have to break the seal on their packaging.

The setup procedure for the AS-400 was nonetheless more involved than that for a step-up transformer or a cable riser—more, even, than for most integrated amps, assuming they don't contain wireless music streamers of their own. But as someone who has, in recent months alone, worn on his sleeve a bilious disdain for needlessly difficult setup regimens, you can take my word: The Micromega AS-400 was relatively easy.

Here's how it went for me: At power-up, the AS-400's pilot light glowed blue and the word AirStream glowed red in six-point type on the digital readout. Approximately 65 seconds later, that word changed from red to blue, suggesting that the AirStream module was ready to go. And it was: When I clicked on my iMac's WiFi icon, in the upper-right portion of its display, I saw that Music was now an available network selection. I duly accepted it.

Footnote 1: A modern ailment: One can see just so many compound words with capitalized second syllables before UpChucking.
Audis Micromega
US distributor: Audio Plus Services
156 Lawrence Paquette Industrial Drive
Champlain, NY 12919
(800) 663-9352