Woo Audio has a very full line of headphone amplifiers that have come to be respected by many knowledgeable headphone aficionados. In 2011, Woo unveiled an amplifier specifically for electrostatic headphones, and particularly aimed at the new Stax SR-009 headphone (Stax’s flagship model), which we have reviewed here. As we said in that review, the SR-009 is easily a contender for “best headphone in the world”, so it makes sense that high-end amplifier manufacturers (Woo Audio, Head Amp, Cavalli Audio, Ray Samuels Audio) are offering products with top-tier headphones such as the SR-009 in mind. Of course, the WES will work perfectly well with other Stax models like the SR-007 Mk II. We recently had three of these new electrostatic amps in the Playback headphone lab and we’re kicking off our coverage with the Woo WES, the first of the amps to arrive at our door.
The WES is a large, two-chassis, fully balanced tube amplifier. The bottom chassis houses the power supply, and uses two 5AR4 rectifier tubes plugged in horizontally and protected by a Plexiglas plate. Woo has provided two on/off switches as a way to reduce the inrush spike when you power the WES on (assuming that you use these one at a time). The lefthand power switch turns on the tube heaters, while the righthand switch turns on the rest of the main power supply (once the tubes have been pre-heated).