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This is something we don't see too often: an entirely new approach to power amplifier design. As Quad points out in its literature for the 405, class-A operation of transistors provides the lowest distortion, but drastically limits the amount of power an output transistor can deliver without overheating. (Most transistor amps use class-AB output operation, in which each of a pair of power transistors handles part of each signal cycle and shuts down during the other part. Imperfect synchronism between the two halves causes the familiar "crossover distortion," which accounts for most solid-state sound. In class-A operation, each output transistor draws current though the entirety of each signal cycle, eliminating the crossover transition but doubling the amount of time current is drawn, and thus tending to cause the transistor to heat up more.)

The cab's outside, the plane leaves in 50 minutes. Let's see...HeadRoom Supreme, HeadRoom Bag, portable CD player, CDs, Etymotic ER-4S Canal Phones....Oh, yeah—mustn't forget luggage or plane tickets. Guess I'm set to go.

MEDESKI MARTIN & WOOD: Friday Afternoon in the Universe
John Medeski, organs, piano, wurlitzer, clavinet; Billy Martin, drums, percussion; Chris Wood, acoustic bass, harmonica, wood flute
Gramavision GCD 79503 (CD only). MMW, David Baker, Jim Payne, prods.; David Baker, eng.; Dr. Toby Mountain, mastering. DDD? TT: 57:06

One of the great imponderables in hi-fi is how much the vibrations of a dynamic loudspeaker's cabinet walls contribute to its overall sound quality. Studies by William Stevens in the mid-1970s showed that, with some speakers, the acoustic output of the enclosure could be almost as much as that from the drive-units. Since then, responsible speaker designers have worked hard either to damp cabinet vibrations or to shift them to higher frequencies where their effect on the music will be less deleterious.