In a Mellow Tone (or Not)

Back in the 1960s, tone controls were considered a must-have feature for audio gear. But in 1974, their reputation sank when famed audio entrepreneur Mark Levinson introduced his JC-2 preamp, which omitted the controls. The pitch was purity—audiophiles had noticed that some gear sounded better with tone controls switched off—and within a few years, the ability to tweak frequency levels had practically disappeared from high-end audio equipment.

In the last 10 years, though, tone controls