Woo Audio WA22 Balanced Transformer Headphone Amplifier

All Tube, Fully Balanced, No Shortcuts

Some headphone amplifiers use tubes for flavor and transistors for the heavy lifting. The Woo Audio WA22 takes the harder road. It is an all-tube, fully balanced, Class-A design, with no transistors anywhere in the signal path. The second generation adds a true preamp function to a design Woo has refined since 2009.

Two 6SN7 driver tubes, two 6080 power tubes and a 5U4G rectifier do all the work. Output reaches 1.5 watts per channel into 32 ohms. That is real power for planars and other hard-to-drive headphones. A switchable high/low impedance setting matches the amp to anything from 8 to 600 ohms.

The outputs are transformer-coupled. That keeps your headphones clear of the tubes' DC voltage, and it holds the drive steady across the whole impedance range rather than letting it sag at one end.

Hand-Built in Brooklyn, Point to Point

Every WA22 is built in Brooklyn, New York. It is wired point to point by hand, not on a circuit board. An ALPS balanced volume control handles level. The design is self-biasing, so tubes can be swapped without measurements or adjustments — which is why tube rolling is much of the appeal here.

The second generation also turns the WA22 into a control center. Balanced XLR preamp outputs, under 50 ohms, let it drive a power amp or a pair of powered speakers. So one volume knob can run both your headphone and speaker systems.

The chassis is anodized aluminum, in black or silver. It measures 12.5" wide, 12" deep and 8.5" tall with the tubes in, and weighs 26 pounds. Give it air above and behind: tubes run hot.

Who Is This Amplifier Best For?

• You own demanding, high-end headphones — 1.5 watts per channel and an 8-600 ohm range drive hard loads that leave smaller amps strained.
• You want a true balanced setup — balanced XLR input, dual 3-pin and 4-pin XLR headphone outputs, and a fully balanced circuit from end to end.
• You want tubes without the maintenance headaches — the self-biasing design means tube swaps need no adjustment or test gear.
• You want one volume control for headphones and speakers — the balanced preamp output runs a power amp or powered monitors.
• You listen mostly on sensitive IEMs, or you want a small desk amp — the size and the power here are more than that job needs, and a smaller design from our headphone amplifiers fits better.

How Does It Connect to Your System?

Connect a source two ways: balanced XLR from a DAC or other balanced component, or standard RCA, which the WA22's phase splitter converts for its balanced circuit. Headphones connect through a 4-pin XLR, dual 3-pin XLRs, or a 1/4" jack, and the high/low impedance switch matches the output to your specific headphones.

To use it as a preamplifier, run the balanced XLR outputs to a power amplifier or powered speakers. Give the tubes a few minutes to warm up, and leave room above the amp for ventilation, as a Class-A tube design runs warm by nature.

Pairs Well With

Building your system? Here are some great companions for the WA22:

• Headphones: This amp deserves a reference-level headphone to match — see our Headphones.
• DAC: A balanced DAC on the XLR input keeps the whole chain balanced — see our Digital-to-Analog Converters.
• Cables: Quality balanced interconnects matter at this level — see our Interconnect Cables.
• Audio Rack: Give this 26-pound amp a stable, ventilated home — see our Audio Racks.

Frequently Asked Questions

What changed in the second generation?

Woo Audio updated the WA22 in 2018 with improved sonic performance and added a balanced preamplifier output, so it can control a speaker system as well as headphones.

What tubes does it use?

Two 6SN7 driver tubes, two 6080 power tubes, and one 5U4G rectifier. Self-biasing makes tube rolling simple.

Can it drive hard-to-drive headphones?

Yes. It delivers up to 1.5 watts per channel into 32 ohms and handles headphones from 8 to 600 ohms, with a high/low impedance switch for the best match.

Do I need a balanced source to use it?

Alongside the balanced XLR input, there's a standard RCA input, and an internal phase splitter converts that signal for the balanced circuit.

Can I use it as a preamp?

Yes. Balanced XLR preamp outputs let the WA22 drive a power amplifier or powered speakers.

What's the warranty?

Woo Audio covers the WA22 with a 3-year limited warranty.

See It in Action

Ryan Ho shares his listening impressions of the second-generation WA22:

The Source AV Design Group walks through the WA22 as both headphone amp and preamplifier:

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Learn More

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