Nuvistors—miniature, small-signal, vacuum tubes made of metal and ceramic—were introduced by RCA in 1959, at the dawn of the transistor revolution. RCA used them throughout the 1960s in its New Vista line of television sets, mostly in the tuner section. But by the early 1970s, solid-state devices had all but replaced tubes, nuvistors included (with a few notable exceptions). Ampex based the electronics of its well-regarded, late-'60s MR-70 open-reel tape deck on nuvistors, which were also used in microphone preamplifiers—in both cases for their very low noise and reputation for reliability and long life. For a time, Conrad-Johnson used them as well. While nuvistors may seem exotic today, they're hardly rare. On eBay you can find for sale hundreds if not thousands of used and new-old stock (NOS) nuvistors, as well as nuvistor sockets, without which the tubes are less easy to implement. (But they can be, and often are, hard-wired into a circuit.)

The British company Chord Electronics has always seemed to me to be audio's crazy uncle: Crazy like a fox, maybe, but definitely marching to their own tune. Their casework design often borders on the gratuitously provocative, challenging audiophiles' ideas about good taste. Yet many of my audio pals swear by the sound of Chord components, and I've heard them shine in many respectable showrooms.

"There are two kinds of music. Good music, and the other kind," Duke Ellington is famously supposed to have said. But that doesn't tell us how to recognize "good music," and it doesn't define good. Nor will this essay. Many have described the music of, say, Mozart or J.S. Bach with such phrases as the music of heaven or the mind of God or—especially Bach's music—that it embodies the basic structure of the universe/existence/reality. I've said such things myself.