Digital Processor Reviews

Sure, Stereophile gets letters to the editor. We also get some colorful responses for our "Manufacturers' Comments" section. (Vince Bruzzese and Roy Hall are literary standouts among their component-making peers.) And, as one of the magazine's Contributing Editors (Audio), I get lots of personal mail from readers seeking my advice. I thought I might share some of these letters with you, and my responses.

The dual subwoofers were bumping and our pant legs were flapping. Only moments before, we'd been treated to a polite viola da gamba. Not now. Resolution Audio's designer, Jeff Kalt, had brought only two discs with him to ensure that his company's Cantata Music Center was functioning properly in my system: Jordi Savall and Hespérion XXI's Altre Follie, 1500–1750 (CD, Alia Vox 9844), and Tool's 10,000 Days (CD, Tool Dissectional/Volcano 81991). After changing a few things around with the chamber music, we'd advanced to the hard rock of Tool.

Oh boy, another new DAC review. Some folks think DACs, once you get past the features, all sound pretty much the same. I mean, it's just digital. Well, they're right. Pretty much. Just as two new cars of a particular make, model, color, and options package both look the same, sitting there on the lot.

But if you discover a ding in the door of one of them, where most folks still see only a new car, you now see the ding. It might have been there all along, undetected the first few times you walked around the car—maybe your buddy even had to point it out to you. It's insignificant in the scheme of all that a new car is, but once you've seen it, you always see it. Now you can easily tell the two cars apart, and we both know which one you'll drive home.

I think any newish company launching yet another expensive (ie, anything over $2000) digital-to-analog converter on the roiling waters of the audiophile marketplace needs at least two things: a truly great product, and a good story to tell. I think Bricasti Design Ltd., of Medford, Massachusetts, has both.

Minnesota pride is a funny thing. As Garrison Keillor points out weekly on A Prairie Home Companion, to be a Minnesotan, the first and crucial step to be taken is that of self-effacement. It is unclear to me whether this is the cause or symptom of Minnesotans ability to endure brutal winters, excel at the creation and consumption of hot dish (which the rest of the God-fearing world knows as casseroles), or their miraculous lineage from generations of Norwegian bachelor farmers. Whatever it is, Minnesotans tend to quietly get their jobs done with little more fanfare than a cup of coffee and a slice of rhubarb pie.

A computer is not optimized for the uninterrupted streaming of audio data. It has rapidly become established wisdom, therefore, that the optimal means of extracting audio data from a computer's USB port is to operate that port in what is called "asynchronous isochronous" mode. This lets the receiving device, such as a digital-to-analog converter (DAC), control the flow of data from the PC. In theory, asynchronous USB operation (not to be confused with the asynchronous sample-rate conversion used in some DACs) reduces jitter to unmeasurable levels, depending on the accuracy of the receiver's fixed-frequency oscillator, which is used to clock the data to the DAC. By contrast, in the alternative and almost ubiquitous USB operating mode, called "adaptive isochronous," while the sample rate of the output data, averaged over a longish period, will indeed be the specified 44.1 or 48kHz, there will be short-term fluctuations, or jitter, due to the oscillator having to change its frequency every millisecond to match the uncertain rate of data flow from the PC.