Woo Audio WA33 Headphone Amplifier and Preamplifier

"BEST Tube Amplifier I Have Ever Heard"

In 2009, Woo Audio introduced two world-class fully balanced headphone amplifiers: the WES electrostatic amp and the WA22 dynamic amp. Both are preferred choices among the most discerning audiophiles. The newly developed WA33 is a state-of-the-art fully balanced headphone amplifier that raises the bar in setting a new reference in music reproduction.

The WA33 is both a headphone amplifier and a line-level preamp. Unlike the vast majority of headphone amplifiers on the market that use vacuum tubes, the WA33 does not rely on a hybrid tube and transistor design. Instead, for maximum sonic richness that harkens back to the best components from the Golden Age of high-fidelity gear, the WA33 glories in a gorgeous all-tube design.

"The sound of the WA33 is something to behold. This is the BEST tube amplifier I have ever heard. So much power, control, detail, speed, and soundstage," raves reviewer drbobbybones at head-fi.org.

"When the headphone amplifier geniuses from Woo Audio launch a new flagship amp, the audiophile world listens," notes reviewer Coolpep at sama3a.com. "I am thrilled by this release."

True Fully Balanced Output-Transformer Design

The WA33 employs a true fully balanced direct-heated triode, Class A, output-transformer design in a compact form factor, featuring a quad of 6C45 tubes for the driver that pushes a quad of 2A3 tubes for the power in an all-tube design. One 5U4G is used as the rectifier tube. It delivers high power to drive demanding headphones to their full potential, while maintaining a low noise floor for use with highly sensitive models. For maximum reliability, the circuitry uses point-to-point wiring.

Tube complement in this model is subject to change due to part availability.

Separate-Chassis Power Supply Raises the Performance Bar

The WA33 shares the same striking appearance of the critically acclaimed WES, where both amplifier units are independent of the power supply. This approach eliminates any interference to critical audio components. Additionally, Woo Audio's internal coupling architecture (ICA) technology allows the WA33 amplifier to merge with the power supply unit without an external umbilical cord to form a single unit in two chassis. The ICA shortens the signal path, and thus significantly reduces unwanted electrical interference and raises sound performance to a level beyond what anyone has experienced in a headphone system.

Reveals the Most Delicate Details

The WA33 reveals the most delicate detail with the highest level of refinement. Complex music passages are handled with ease and authority. The expansive soundstage, holographic imaging, and rich tones that are pristine, natural, and vivid create a sense of realism that gives the user a euphoric listening experience. With the WA33, music comes to life.

Preamp/Headphone Connections

The WA33 provides a convenient selection of versatile outputs and inputs for preamp or headphone use. It has a user selectable high impedance or low impedance balanced XLR preamp output, a user selectable high level or low level headphone output, and two pairs of balanced XLR inputs plus one pair of unbalanced RCA inputs. The headphone outputs consist of one 1/4" (6.3mm) TRS, one 4-pin XLR, and one dual 3-pin balanced XLR.

Product Features

Overview

Fully Balanced Direct-Heated Triode, Class A, Output-transformer design
Point-to-Point wiring
The Internal Coupling Architecture (ICA) merges amplifier and power supply without an external umbilical cord to form a single unit.
Amplifier unit mounted permanently on the power supply
User selectable high impedance or low impedance XLR output
User selectable high level or low level headphone output
User selectable inputs: XLR or RCA

Tube Complement

Four 2A3 power tubes in matched quad
Four 6C45 driver tubes in matched quad
One 5U4G rectifier tubes
Tube complement in this model is subject to change due to part availability

Connections

Two XLR inputs, one RCA input
One XLR preamp output
Headphone outputs: one 1/4" (6.3mm) TRS, one 4-pin XLR, one dual 3-pin XLR

Product Specs

Headphones impedance: 8-600 Ohms
Frequency response: 10Hz- 60kHz, -2dB
Preamp maximum output: 10V + 10V balanced
Preamp output impedance: 50 ohms
Power output: up to 10 watts per channel
Signal/Noise: > 95 dB
THD: < 0.05%, 1kHz
Voltage: AC 120/240V, 50/60 Hz
Power consumption: 150 watts
External dimensions: 17.5"(W), 12"(D), 7.5"(H), add 5" to 6" with tubes installed
Weight: 50 lbs

Product Warranty

Parts & Labor

1 Year Warranty on Product and New Production Factory Tubes | 3 Years for Purchases After January 1st, 221

3-Day Warranty on NOS Tubes

Woo Audio Warranty Information

Product Manual

	Woo Audio WA33 Manual (PDF Format)

"The WA33 is a fantastic vacuum-tube power headphone amplifier/preamplifier that Woo Audio should be very proud of. I think anyone who is able to come up with the $8,000 asking price for this headphone amplifier/preamplifier in its standard edition and decides to purchase this component has made an excellent decision. This is because the Woo Audio WA33 will allow this music lover to own a headphone amplifier that will be able to transport them to another world, one where the music is the only thing that matters. That the Woo Audio WA33 can double as a preamplifier is icing on the cake."

- Tom Lyle, enjoythemusic.com, April 2019

2019 Editors' Choice Award – The Absolute Sound

"Worthy of pairing with the finest headphones, as it offers," says Jim Hannon. “Lots of fine detail, as well as exceptional clarity, dynamic headroom, and bass extension and control."

- The Absolute Sound, March 2019

"I can imagine other audiophiles using the WA33 as a balanced linestage in their reference systems. It’s that good!"

"The Woo Audio WA33 is a terrific headphone amplifier, as well as a balanced linestage preamplifier suitable for use in the finest audio systems. It should drive any dynamic or planar-magnetic headphone without a problem and the overall sound is glorious with a rich, but naturally detailed tonal balance, explosive dynamics, and powerful extended bass. Better still, its superb performance will keep you listening late into the night."

– Jim Hannon, The Absolute Sound, December 2018

"The WA33 could very well be the best sounding headphone amplifier ever to make its way into the lab..."

"If you have the disposable income, highly recommended."

- audio-head.com, July 18, 2018

"The Woo Audio WA33 is exactly what a tube amplifier should sound like. It’s the right amount of everything. It’s not overly warm or sweet and doesn’t mask the finer details of the music. It improved the fidelity of not just the power-hungry headphones but those with lower sensitivities as well. The WA33 fills the music with textural colors, a naturalistic body, and improved dynamics across all genres. It doesn’t sound 'tubey' in the traditional sense but perfects the balance required to provide just enough midrange bloom to be emotive and engaging. While this bloom sounds a bit artificial with some amps, there’s an accuracy and tastefulness in the coloration of the WA33. It presents a cozy and dreamy sound without losing accuracy and intent. This is especially the case with live music."

"This is the best tube headphone amplifier I’ve ever heard and will be the end-game headphone amplifier for many. The sound of the Woo Audio WA33’s is simply unforgettable."

- Jay Luong, Audio Bacon, December 29, 2017

"The sound of the WA33 is something to behold. This is the BEST tube amplifier I have ever heard. So much power, control, detail, speed, and soundstage."

- drbobbybones, head-fi.org

"When the headphone amplifier geniuses from Woo Audio launch a new flagship amp, the audiophile world listens… I am thrilled by this release."

- Coolpep, sama3a.com