Woo Audio WA7 Fireflies

Latest version since March 16, 2016.
Newly designed DAC and improved amplifier circuitry

Pure tube Class-A headphone amplifier with 24-Bit, 384K USB Digital-to-Analog Converter

WA7 Fireflies in silver WA7 Fireflies in black

The WA7tp (left) is a vacuum tube external linear power supply utilizing two 12AU7 tubes as rectifiers.

WA7 Fireflies with the WA7tp vacuum tube power supply

"this little amp sounds powerful" - The Audiophiliac

"This is possibly the most linear
DAC and headphone amp I've heard " - Positive Feedback

"the WA7 is practically a steal in terms of
sound quality and physical presentation. " - HP Soundings

"The WA7 is a thing of museum-grade beauty and simplicity." - Ken Rockwell

"WA7 "Fireflies" are fully featured DACs with
world-class vacuum tube amplifiers." - voted the Best DAC by Lifehacker

"The Fireflies is very highly recommended for anyone buying their first,
or even possibly their last, reference amplifier." - Dagogo

"For anyone wanting a high-performance, compact and aesthetically pleasing ...
head-phone audio system, there's no better choice than the WA7." - Tone Audio

The Woo Audio WA7 “Fireflies” Amp/DAC is a combination of high performance vacuum tube headphone amplifier with a built-in USB Digital-to-Analog Converter. It is a pure tube design, utilizing 6C45 tubes in a class-A, single-ended topology, with transformer coupled outputs. There are no semiconductors used in the entire amplification path. The D/A converter is designed to be capable of up to 24-bit/384k sampling rates. This maintains pure data integrity, which is transmitted via standard high speed USB 2.0 interface operating in asynchronous mode.

The high quality construction features include a pair of Nickel Alloy core output transformers, all-aluminum chassis with no screws visible from any viewing angles, a remote-controlled linear external power supply for amplification circuitries, a custom built toroidal power transformer, and multi-layer military grade PCBs.

The dedicated port for in-ear-monitors carries a full range of volume controls ensuring minimal noise. Despite its incredibly compact size, “Fireflies” is a power-house with the capacity to drive almost any demanding audiophile headphones. To accommodate different system setup needs, “Fireflies” can also be used as a stand-alone D-A Converter.

WA7 Fireflies Owner's Manual (PDF) pdf-icon

WA7tp Tube Power Supply Owner's Manual (PDF) pdf-icon

 USB drivers for Windows XP/Vista/7/8/10, or here usb logo

Price $999* / $1599**

* Includes a WA7p solid state power supply
** Includes a WA7tp vacuum tube power supply

☐ One (1) year limited warranty cover amplifier and power supply parts and defects, thirty (30) days for tubes. No coverage on glass except for defects on arrival.

☐ Shipping address outside the of Contiguous U.S. will be billed for additional shipping cost.

What's in the box? 1 unit of WA7 Fireflies, 1 unit of External Power Supply of user choice, 1 piece of tube protection glass, 4 pieces of anti-slip glass protection pads, 1 pair of matched Sovtek 6C45, 1 Umbilical power cord, 1 polish cloth. AC power cord, USB, and interconnection cables are not included.

6C45 Gold is out of stock, avail in early Jan 2018.

Upgrade tubes (LIMITED offer): Electro Harmonix 6C45 Gold Plated Pins matched pair, $140

Tubes are matched in a WA7 Fireflies for the best results.

Upgrade tubes 2: Reflector brand 6C45 NOS (for amplifier unit) matched pair, $55

Tubes are matched in a WA7 Fireflies for the best results.

Stock tubes: RCA 5963 (12AU7) NOS (for WA7tp tube power supply) matched pair, $55

Tubes are matched in a WA7tp tube power supply for the best results.

A power-house to drive even the most demanding full-sized headphones, along with a dedicated mini phone jack tailored for in-ear-monitors.

Pure tube design without the use of semi-conductors in the amplification circuitry. The 6C45 triode acts as both driver and power tube.

High fidelity listening experience in the most simplistic form

The USB input supports up to 24/384k hi-res playback. The RCA connectors can be used either as analog inputs or as D/A outputs. Both in/out signals are user selectable on the back panel.

The linear external power supply provides pristine energy to the amplifier. It can be placed where ever you please to keep the simplicity of the unit.

*NEW* WA7tp tubed power supply takes sonic performance to a new level. Same gorgeous design and dimension as WA7 Fireflies. Hefty ON/OFF power button that feels substantial when pressed

We chose the commonly available 12AU7 tube for the convenience of allowing the user to tubes swap among other brands available for a personalized, tailored sound signature.

Moving up from the standard solid state power supply (PSU) to the WA7tp (vacuum tubes PSU) would improve the overall sound quality of our award-winning WA7 Fireflies. You should notice, enhanced the stereo separation, smoother treble, more air, more effortless sound.

WA7 Fireflies brings power, simplicity, beauty, and elegance to your desktop workspace

A thick block of superior quality, high clarity glass is provided to protect the tubes, while maintaining a clean and elegant aesthetic.

Available in Black and Silver with Clear glass.


  • All-tube design (not hybrid)
  • Class-A, Single-ended Triode transformer-coupled
  • Improved analog circuit
  • 6C45 x2 driver/power tubes, 12AU7 x2 rectifier tubes for WA7tp tube power supply upgrade
  • Teflon tube sockets
  • ESS SABRE Reference DAC (ES9018K2M)
  • XMOS xCORE-AUDIO asynchronous USB compatible with Mac, PC, Android and iOS devices*
  • Headphones impedance : 8-600 Ohms
  • Input impedance: 100 Kilo-Ohms
  • Hi-res audio playback up to 24-bit/384kHz
  • Inputs: 1 high-retention USB (Type-B) input, 1 RCA
  • Outputs: 1 1/4" and 1 1/8" headphone outputs, 1 RCA (same connector as the input)
  • Max output: approx 1 watt @ 32 ohms
  • Frequency response: 11Hz to 27kHz, +/-0.5dB
  • Distortion: <0.03%
  • S/N: 95dB
  • Power consumption: 25W max
  • Mains supply: 100-120V, 220-240V, 50/60Hz, user selectable
  • Finish: Anodized aluminum
  • DC cord length: 4.25 ft or 1.3 m
  • Dimension: AMP: 4.8" L x 4.8" W x 5.1" H with glass
    PSU: 7" L x 3.5" W x 2.2" H
  • Weight: AMP - 5.3 lbs / 2.4kg, Glass - 3.3 lbs / 1.5kg
    PSU - 2.8 lbs / 1.4kg
    WA7tp vacuum tube PS - 9.4 lbs / 4.3kg


  • Handmade output transformer with Nickel Alloy core
  • 24-Bit, 384kHz high resolution playback
  • Ultra-low jitter USB 2.0 runs on Asynchronous mode
  • High and low impedance output facilitated via toggle switch on back panel
  • Open load protection will automatically engage to prevent the amp from damaging when no headphones are plugged in
  • Multi-functional switch for USB input, RCA input, and RCA output via D/A.
  • The RCA connectors can be used either as RCA analog inputs or USB DAC preamp outputs
  • All-aluminum chassis with no screws visible from any viewing angles
  • High clarity tube protection glass
  • Multi-layer military grade PCBs
  • Driver for Windows Vista/XP/7/8/10
  • USB Audio Class 2.0 is natively supported by Apple OS X version 10.6.4 and above without installing driver