Digital Processor Reviews

The $799 Theorem was originally shown at the 1992 WCES in a very small chassis that prohibited adding features or upgrades. Sumo has since become more ambitious, putting the Theorem in a full-sized chassis and offering several upgrade options that would have been impossible in the truncated version.

Looking at the Digital Link II's build quality and circuitry, it's hard to believe that it can sell for $499 at retail. The Digital Link II shares the same appearance as PS Audio's SuperLink and UltraLink processors, but has a 4"-shorter chassis. The ¼"-thick front panel uses PS Audio's familiar touch-sensitive switches that turn the unit on and select between coaxial and optical inputs. LEDs above these switches indicate when the unit is locked to the digital source. A third LED illuminates when power is applied.

Though their first CD player featured a vacuum-tube output stage, California Audio Labs is recently known for making good-sounding, moderately priced solid-state CD players, like the Icon Mk.II that Jack English reviewed in July 1992 (Vol.15 No.7). The Sigma, a $695 tubed D/A converter, furthers their reputation in both areas.

Since the first digital processor on the market using UltraAnalog DACs appeared (the $12,000 Stax DAC-X1t, reviewed in August 1990, Vol.13 No.8), there has been a proliferation of good-sounding processors using this extraordinary—and expensive—part. Among these are the Audio Research DAC1, Audio Research DAC1-20, VTL Reference D/A, and the groundbreaking Mark Levinson No.30 reviewed last month.

Over the past two and a half years, I've auditioned and reviewed a number of digital audio products. It has been a fascinating experience both to watch digital playback technology evolve and to listen to the results of various design philosophies. The road to more musical digital audio has been a slow and steady climb, with occasional jumps forward made possible by new techniques and technologies. Making this odyssey even more interesting (and confounding), digital processors seem to offer varying interpretations of the music rather than striving toward a common ideal of presenting what's on the disc without editorial interjection.

No, the $399 price listed in the specification block isn't a misprint. And yes, the Audio Alchemy Digital Decoding Engine v1.0 is indeed a full-function outboard digital processor. And since this is the August issue, not April, you can stop worrying that this review is some kind of joke.

The $399 Digital Decoding Engine is for real.

The past 12 months have seen some remarkable developments in digital playback. Standards of digital musicality are far higher than they were a year ago, both on an absolute performance basis and in terms of what you get at various price levels. No other component category has seen such tremendous gains in value for money or number of new products introduced. It seems hard to believe that since Vol.13 No.6 (12 issues ago), we've reviewed such noteworthy digital processors as the Meridian 203, Proceed PDP 2, Stax DAC-X1t, Theta DSPro Basic, Wadia X-32, Esoteric D-2, PS Audio SuperLink, and VTL D/A. Each of these converters brought a new level of performance to its price point—or, in the case of the Stax and VTL, established a new benchmark of ultimate digital performance.

Just as these units provided stiff competition for previous products, so too will they come under the assault of improving technology. The art of digital processor design is so young that we can continue to expect further improvements coupled with lower prices as designers move up the learning curve.