The dying CD format is unlikely to be replaced by any other disc format. DVD-Audio barely got off the starting blocks before it died its own quick death, while SACD, while still holding on, has never gained widespread acceptance. Instead, the future of audiophile-grade digital playback is in digital music files stored on and played by home computers connected to high-grade external D/A converters.

Audiophiles have plenty of choices when it comes to selecting a top-quality DAC, but one of our favorites is Ayre Acoustics’ QB-9 USB DAC, which Peter Roth reviewed on our sister site Ultra Audio late last year. Since then, publisher Doug Schneider and other SoundStage! Network writers have adopted the QB-9 as their primary digital source.

The QB-9 is compact, measuring 8.5"W x 3"H x 11.5"D and weighing about five pounds. Its build quality is excellent, and its brushed-aluminum casework is smart. Peter spelled out the QB-9’s many technical features in his review, but a few of them of particular interest to audiophiles are worth reiterating here: With single-ended and balanced outputs, the QB-9 can swing either way and connect to either type of system; it offers two of Ayre’s Minimum Phase digital filters, selectable via a rear-panel DIP switch, for time-accurate reproduction of the audio signal; and, finally, incorporated into its USB input is the Streamlength Asynchronous Transfer Mode technology, developed by Wavelength Audio’s Gordon Rankin. Asynchronous transfer (as opposed to asynchronous data-rate conversion) is widely considered the best way to implement USB connectivity, due to its extremely low jitter. The units that Peter reviewed and that Doug now has are of the original model, which natively supports sample rates of 44.1, 48, 88.2, and 96kHz. Ayre recently released a new version of the QB-9 that is identical except for the digital-input board, which now supports 176.4 and 192kHz datastreams as well. Original QB-9s can be upgraded to the latest iteration for $250.

By everyday consumer standards, the QB-9’s retail price of $2750 might seem astronomically high. After all, a decent computer can be had for a few hundred bucks, and comes with a soundcard with a D/A section already built in. But such soundcards can’t deliver the QB-9’s audiophile sound quality. In fact, the QB-9 compares favorably with the very best DACs on the planet. By high-end standards, this makes it a bargain.

Peter Roth praised the QB-9’s sound quality, feeling that, overall, it bettered the performance of the far more expensive DACs he had on hand. At the end of his review he said, “Providing significantly greater performance than any similarly or lower-priced alternative, and undoubtedly one of the best computer-audio DACs now available regardless of price, the QB-9 is a watershed component in this watershed year.” Doug Schneider found that the QB-9, hooked up to a Sony Vaio laptop, offered the best sound he’s ever heard, inching past even the Simaudio Moon Evolution SuperNova CD player he’d been using as a reference for years, and which retails for more than twice the QB-9’s price. Doug was particularly impressed with how resolving and transparent the QB-9 is without ever sounding hard, irritating, or fatiguing. He was also taken with how easy it is to set up, and how flawlessly it works with his Windows computer. “No hiccups whatsoever,” he said. “Within minutes, it was working.”

The only downside to the QB-9 is that it has only a single USB input. Those who might want to hook up additional digital sources, such as a transport, via coax, TosLink, or AES/EBU connections, can’t. Ayre makes no apologies -- the QB-9 was designed from the ground up to provide state-of-the-art digital playback via a USB connection, in order to embrace this new and exciting age of computer-based digital audio. They’ve succeeded admirably. The QB-9 created a big stir when it was released over a year ago, and it’s still one of the very best USB DACs you can buy today.

Manufacturer contact information:

Ayre Acoustics, Inc.
2300-B Central Avenue
Boulder, CO 80301
Phone: (303) 442-7300

Website: www.ayre.com