When I began my journey into audiophilia, I was in awe of the Audio Research Corporation's flagship SP preamplifiers. As I sat there in the early 1980s with my modest Apt Holman preamp, all of my friends had ARC SP6Bs. By today's standards, the SP6B was colored, did not portray a realistic soundstage, and lacked sufficient gain to amplify the low-output moving-coil cartridges of the day. But it had an intimacy in the midrange that was intoxicating. (Still considered a classic design by many, the SP6B's price on the used market has remained virtually unchanged for 30 years.) Then, still in the early '80s, ARC raised the bar with the SP-10 ($3700). It had 15 tubes and an outboard power supply, and set a new standard for delicacy, drama, and authority. (John Atkinson still has the SP10 he bought in 1984.)

Audiophiles spend a lot of time thinking about the law of diminishing returns. We'd all agree that spending $1000 to replace an iPhone and generic earbuds with one of Stephen Mejias's "Entry Level" systems is in the early, steep part of the curve: a huge jump in performance for relatively small investment. We'd also agree, or at least suspect, that after you've spent that $1000, the curve gets a lot flatter. What we don't agree on is the shape of the curve between these points. The ideal situation is to find the knee: the point at which the curve's slope changes dramatically. At the knee, we've gotten most of what we want, and the next increment of performance improvement is disproportionally expensive.

Paul Bley's Play Blue: Oslo Concert (on the ECM label) is a bracing solo piano album. Think Keith Jarrett, with less Rachmaninoff and more Monk, but the distinctions sway on the margins. Bley too is a romantic improviser, immersed in jazz idiom but classically trained (and he lets it show, though less showily than Jarrett).

Before there were jam bands, before the term even existed in fact, there was a fabulous, funky assemblage called Little Feat.