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.