Jim Austin

It's not surprising that many people, like me, love nice cameras and good stereo gear. In my worse moments, I attribute this to mere consumerism: We love expensive stuff and the thrill of buying something new, whether for reproducing music or creating visual images. In my better moments, it's clear to me that there's more than that to this common taste for audio and photography, and more to the hobby of so-called perfectionist audio.

In the March 2018 issue, Art Dudley admired the sound quality of Ayre Acoustics' KX-5 Twenty preamplifier, but didn't love some of its operational aspects. I've staged this Follow-Up as a putative face-off between the Ayre and my current reference preamplifier, the PS Audio BHK Signature, which I reviewed in the June 2017 issue.

The right thing at the wrong time is the wrong thing.—Joshua Harris

The sampling theory formulated by Claude Shannon in the late 1940s had a key requirement: The signal to be sampled must be band-limited—that is, it must have an absolute upper-frequency limit. With that single constraint, Shannon's work yields a remarkable result: If you sample at twice that rate—two samples per period for the highest frequency the signal contains—you can reproduce that signal perfectly. Perfectly. That result set the foundation for digital audio, right up to the present. Cue the music.

When you come to a fork in the road, take it.—Yogi Berra

Over one busy week in 1986, Karlheinz Brandenburg laid the foundation of a technology that a few years later would upend the record business. Brandenburg, a PhD student in electrical engineering at the Friedrich-Alexander University Erlangen-Nuremberg, was figuring out how to code digital music efficiently enough that it could be delivered over digital telephone lines. A patent examiner had concluded that what the application proposed was impossible, so over a week of late nights, Brandenburg produced the proof of concept and more. It was another decade before the technology—MPEG-2 level III, more commonly known as MP3—would find its true home, the Internet.

Loss is nothing else but change, and change is Nature's delight.—Marcus Aurelius

Master Quality Authenticated (MQA), the audio codec from industry veterans Bob Stuart and Peter Craven, rests on two pillars: improved time-domain behavior, which is said to improve sound quality and what MQA Ltd. calls "audio origami," which yields reduced file size (for downloads) and data rate (for streaming). Last month I took a first peek at those time-domain issues, examining the impulse response of MQA's "upsampling renderer," the output side of this analog-to-analog system (footnote 1). This month I take a first look at the second pillar: MQA's approach to data-rate reduction. In particular, I'll consider critics' claims that MQA is a "lossy" codec.

A recent post on Roon's forums drew my attention to an apparently new category at Apple Music, Apple's streaming service. The post pointed to an Apple Music page listing music curated by the ECM music label. After ECM "Playlists," "New and Noteworthy," and "Recent Releases" is a section labeled "High-Resolution Masters."

I don't think I've ever seen an audio debate as nasty as the one over Master Quality Authenticated (MQA), the audio-encoding/decoding technology from industry veterans Bob Stuart, formerly of Meridian and now CEO of MQA Ltd., and Peter Craven. Stuart is the company's public face, and that face has been the target of many a mud pie thrown since the technology went public two years ago. Some of MQA's critics are courteous—a few are even well-informed—but the nastiness on-line is unprecedented, in my experience.