SINFONIA
Comebacks by musical legends are almost always a letdown, but there's one '60s icon that's performing, and looking, even better today than it did 40 years ago: the tube amplifier. Although almost made extinct in the 1970s by cheaper transistor-based amps, vacuum tubes (also known as valves) are back in the mix for a growing number of high-end audio companies. This isn't just sonic nostalgia: audiophiles have long claimed that tubes pump out warmer, smoother sounds — a result of the low-level distortion that tubes generate — than transistors. If your music goes down these tubes, it's guaranteed to amplify your...