The remedy is straightforward: You go back to the master. This is one reason that rereleases of classic albums are promoted as having been painstakingly remastered from the original tapes. It’s why consumers of new technologies, like CDs in the 1980s, are eager to hear familiar music properly recaptured for the format. Right now, sound-savvy consumers are taking the next leap forward into high-resolution audio, which can deliver streaming music of unprecedented depth and detail. But you can’t simply up-convert existing digital files to higher resolution. You have to return to the master and recapture it at a higher bit rate.

But the case for masters extends beyond arguments about bit depth and frequency ranges audible only to dogs. It enters the realms of aesthetics and phenomenology. Simply put, the master of a recording is that recording; it is the thing itself. The master contains the record’s details in their purest form: the grain of a singer’s voice, the timbres of instruments, the ambience of the studio. It holds the ineffable essence that can only truly be apprehended when you encounter a work of art up-close and unmediated, or as up-close and unmediated as the peculiar medium of recorded sound permits. “You don’t have to be Walter Benjamin to understand that there’s a big difference between a painting and a photograph of that painting,” Zax said in his conference speech. “It’s exactly the same with sound recordings.”

The comparison to paintings is instructive. With a painting, our task as cultural stewards is to hang the thing properly, to keep it away from direct sunlight, to guard it from thieves. A painting must be maintained and preserved, but only in rare cases will a technological intervention improve our ability to see the artwork. If you were to stand before the Mona Lisa in an uncrowded gallery, you would be taking in the painting under more or less ideal circumstances. You will not get a better view.

In the case of a recording, a better view is possible. With recourse to the master, a recording’s “picture” can, potentially, be improved; the record can snap into sharper focus, its sound and meaning shining through with new clarity and brilliance. The reason is a technological time lag: For years, what people were able to record was of greater quality than what they were able to play back. “Most people don’t realize that recording technology was decades more sophisticated than playback technology,” Sapoznik says. “Today, we can decode information off original recordings that was impossible to hear at any time before.”

The process of revisiting and decoding can transfigure the most familiar music. In May 2017, a new box set of the Beatles’ “Sgt. Pepper’s Lonely Hearts Club Band” was released to mark the album’s 50th anniversary. “Sgt. Pepper’s” is one of the most famous recordings in history, but the version most listeners know is the stereo mix, which was of secondary importance to the Beatles, their producer George Martin and his engineer, Geoff Emerick. It was the mono mix that consumed the Beatles’ attention, and it is to those materials that the box set’s producer, Martin’s son Giles, returned, creating a fresh stereo mix from the mono masters. “The job was to strip back layers, to get back to that original sound and intent,” he says. “The detail we can garner from the mix compared to what they could have done 50 years ago is fantastic.”

The result is a vivid new “Sgt. Pepper’s.” In certain quarters, the album has been regarded as twee, but Giles Martin’s mix reveals a burlier rock ’n’ roll record. The box set opens new vistas on the album’s themes and adds force to its pathos. The opus “A Day in the Life” sounds more ominous than ever, a portent of late ’60s chaos, of the storm gathering on the other side of the Summer of Love. These epiphanies would not have been possible without masters. “Working without the master tapes,” Martin says, “would be like a chef having to use precooked food.”

The “Sgt. Pepper’s” masters are kept in a secure location in London. The tape boxes are marked with recording notes that helped guide Martin’s mixing decisions. The tapes themselves feature additional recordings — alternate versions, overdubs, studio chatter — that were included on the rerelease. Tens of millions of copies of “Sgt. Pepper’s” have been sold over the years; it may seem precious to place special value on the original of a record that is so well known and ubiquitous. But the masters in the London archive are unique. They have greater fidelity than any copy of “Sgt. Pepper’s” that is out in the world. They have more documentation than any version anywhere. And the masters contain more Beatles music too.