Audacious Audio

What better way to celebrate the expiration of a noncompetition clause than to debut a product that has no competition? That's what Dan D'Agostino appears to have done with his Momentum monoblock amplifier ($55,000/pair)—his first new product since leaving Krell, the company he cofounded more than 30 years ago.

For as long as I've known about high-end audio, I've put Dan D'Agostino, co-founder of Krell, on the same pedestal reserved for the likes of Frank McIntosh, Saul Marantz, Avery Fisher, H.H. Scott, and Sidney Harman. The reason is simple: Dan's the man whose achievements at Krell led me from the harsh sound of my first high-end amp into another dimension, one of truly musical sound reproduction.

As the 2009 Consumer Electronics Show neared its end, I wandered into Blue Light Audio's room, which was dominated by the innards of darTZeel's new NHB-458 monoblocks—think of a 3D "exploded" diagram and you'll be on target. So impressive was that display of brute engineering that I almost didn't notice the amplifier that was actually making the music: the CTH-8550 integrated ($20,300).

A recent (unpublished) letter to the editor argued that the reference for audio perfection is the sound of real instruments in a real space. The writer claimed that, since the art and/or science of audio is advancing, and because it is a "scientific truth" that the closer you get to perfection, the less divergence there is components, that therefore there should be less difference in sound among the components listed in Class A of Stereophile's "Recommended Components" than among those in Class B, much less Class C. This should be true of loudspeakers, he said, but even more true of top-rated amplifiers, since "they inherently have less divergence."

What's the point of reviewing a pair of monoblock amplifiers that costs more than most people spend on two or even several cars— and far more than most audiophiles spend on an entire music system? That's a good question. Another is: Why should I write this review when, just seven years ago, I reviewed a pair of darTZeel monoblocks that look exactly like this new pair?

I realize that products such as the darTZeel NHB-468 ($170,000/pair) are for the very few, but the very few include far more people throughout the world than you may realize— people who can afford such costly audio products and who do buy them. I know, because in my travels I've met a lot of them, and they deserve to read reviews of products they're considering buying—things most of us can only dream of owning.

It's now 10 years since the launch of the two high-resolution audio disc formats, SACDhttp://www.stereophile.com/asweseeit/164">SACD; and DVD-Audiohttp://www.stereophile.com/asweseeit/1099awsi">DVD-Audio;. Yet, perhaps partly because both were hobbled">http://www.stereophile.com/asweseeit/257">hobbled in various ways to please the record industry, perhaps partly because too many supposed hi-rez releases sounded no better than CD, and perhaps partly because record retailers weren't sure how to display the formats to their best advantage, neither took off in any substantive way. DVD-A disappeared, and SACD survived only as a niche format for high-quality classical releases in both two- and multichannel forms. As we got deeper into the same decade, digital technology, despite various sparks and flashes, went into the doldrums. Mainstream digital technology was increasingly concerned with squashing the music into fewer and more portable bits, not with increased sound quality. Even the concept of "CD sound quality" began to seem an unattainable goal, as MP3">http://www.stereophile.com/features/308mp3cd">MP3 files became the dominant music carrier.

It has been 20 years since I first became aware of the British company Data Conversion Systems, which manufactures audio products under the dCS brand. Rather than use off-the-shelf conversion chips, the groundbreaking dCS Elgar D/A converter, which I reviewed in our July 1997 issue, featured a then-unique D/A design that they called a Ring DAC. This featured a five-bit, unitary-weighted, discrete DAC running at 64 times the incoming data's sample rate—2.822MHz for 44.1kHz-based data, 3.07MHz for 48kHz-sampled data and its multiples—with upsampling and digital filtering and processing implemented in Field Programmable Gate Arrays (FPGAs). Oversampling to a very high sample rate allows the word length to be reduced without losing resolution, and use of a low-bit multi-bit DAC makes for very high accuracy in the analog voltage levels that describe the signal. (If this seems like voodoo, for a given signal bandwidth, bit depth and sample rate are related. To oversimplify, double the rate, and you can reduce the bit depth by one bit while preserving the overall resolution.)