Woo WES Balanced Electrostatic Headphone Amplifier - Generation 2 - Silver

Built for the Rarest Kind of Headphone

Electrostatic headphones don't work like normal headphones. Instead of a voice coil, they drive an almost weightless film with high voltage, and they need a special amplifier to do it. The Woo Audio WES is that amplifier at its most serious: a fully balanced, Class-A, all-tube electrostatic amp delivering up to 1,300Vrms, with two Stax Pro-bias (580V, 5-pin) outputs for electrostatic headphones from Stax, Audeze, HiFiMan, and Dan Clark Audio.

Twelve tubes do the work: four EL34 power tubes, four 6SL7 drivers, two 12AU7 phase inverters, and two 5AR4 rectifiers. This second generation adds a matched quad of output chokes wound with single-crystal copper, an upgrade Woo credits with better clarity, a wider soundstage, and stronger dynamics and control.

Two Chassis, Forty Pounds of Commitment

Like Woo's other statement amplifiers, the WES splits its design across two chassis: the amplifier section and a separate power supply, keeping transformer noise away from the high-voltage audio circuit. Each chassis is 16.5" wide and 12" deep, and together they weigh 40 pounds.

Construction follows Woo's house method: hand-built in New York with point-to-point wiring, no circuit boards in the signal path, and a self-biasing design so tube swaps need no adjustment. Two balanced XLR inputs and one RCA input handle your sources, and both headphone outputs are live, so two people can listen at once. A premium parts upgrade with V-Cap capacitors is available at build time. The anodized aluminum chassis comes in silver or black.

Who Is This Amplifier Best For?

• You own (or are buying) electrostatic headphones — the WES is a dedicated electrostatic amplifier with two Pro-bias outputs, made for exactly this job.
• You want a true balanced, all-tube signal path — fully balanced Class-A from input to output, with twelve tubes and no circuit boards.
• You share your system — both outputs are active at once, a rarity among electrostatic amps.
• You plan to keep it for decades — hand-built point-to-point construction, a 3-year warranty, and tube types with deep production history.
• If your headphones are conventional dynamics or planars, the WES won't drive them at all — it's electrostatic-only. Look at the WA22 or WA5-LE instead.

How Does It Connect to Your System?

Connect balanced sources to the two XLR inputs or a single-ended source to the RCA input, then plug your electrostatic headphones into either of the two 5-pin Pro-bias outputs. There's no impedance switch or gain setting to configure; the WES is purpose-built for 580V Pro-bias headphones.

Place both chassis with ventilation in mind, twelve tubes in Class-A operation generate real warmth, and give them a few minutes to warm up before critical listening.

Pairs Well With

Building your system? Here are some great companions for the WES:

• Headphones: A statement electrostatic deserves a statement transducer — see our Headphones.
• DAC: A balanced reference source completes the chain — see our Digital-to-Analog Converters.
• Cables: Quality balanced interconnects matter at this level — see our Interconnect Cables.
• Audio Rack: Two chassis need a sturdy, ventilated home — see our Audio Racks.

Frequently Asked Questions

Will this work with my regular headphones?

No. The WES drives electrostatic headphones only, via two 5-pin Stax Pro-bias (580V) outputs. Dynamic and planar headphones need a conventional amp like the WA22.

Which electrostatic headphones does it support?

Pro-bias models from Stax, Audeze, HiFiMan, and Dan Clark Audio, any headphone using the 5-pin 580V Pro-bias standard.

What tubes does it use?

Four EL34 power tubes, four 6SL7 drivers, two 12AU7 phase inverters, and two 5AR4 rectifiers. The design is self-biasing, so swaps need no adjustments.

What changed in the second generation?

A matched quad of output loading chokes wound with single-crystal copper, which Woo credits with improved clarity, soundstage, dynamics, and control.

Can two people listen at once?

Yes. Both Pro-bias outputs are active simultaneously.

What's the warranty?

Woo Audio covers the WES with a 3-year limited warranty.

See It in Action

Joshua Valour spends time with the second-generation WES:

Head-Fi's Jude Mansilla pairs the original WES with the legendary Stax SR-009:

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Learn More

Want to learn more about electrostatic headphones, headphone amplifiers, or building a reference headphone system? Visit our Learning Center for guides, tips, and expert advice.