"Musical Fidelity X-10D" it said on the box. No, this is not bathtub mildew remover or laundry detergent. Actually, it's hard to figure out exactly what it is. The box is little help. Musical Fidelity calls the X-10D "the missing link," a "pure Class A CD-player accessory."
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.)
Last September, in Vol.15 No.9, I started my quest for the Ultimate Kilobuck Tube Amp with reviews of the $995 Panor/Dynaco ST70-II and the $1695 Nobis Cantabile. While neither really fit the bill—the Dynaco fell a bit short in terms of sonics, while the Nobis was priced a bit higher than a thou—they got me thinking of the Ultimate Kilobuck Tube Preamp. Because the greatest amp in the world can only sound as good as whatever drives it, and there's no sense looking for a kick-ass affordable tube amp if you're going to play Scrooge McDuck when it comes to the preamplifier.
Lars recently received a device that looks and works like a $25 digital alarm clock and is said to subtly improve the overall sound of one's system. It's the ElectroTec EP-C, from a company called Coherence Industries.
Editor's note: When Jonathan Scull reviewed the Shun Mook devices back in 1994, he unleashed a hailstorm of controversy that continues to this day. Below is his original report along with some of the follow-up articles and fallout.