The multi-award winning WA7d Fireflies Duo has been an audiophile favorite since its introduction in 2014. It delivers high-performance sound, premium build quality, and beautiful design in a compact form factor. To celebrate the success of WA7d Fireflies Duo, we have temporarily reduced the price to $799. There is no better time than now to get a world-class headphone amplifier and DAC to enjoy your music collection.

Woo Audio WA7d Fireflies Duo

Pure Class-A tube headphone amplifier with 32-Bit, 192K USB Digital-to-Analog Converter
Dual digital inputs with USB and Optical

WA7d Fireflies in silver WA7d Fireflies in black

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

WA7d Fireflies with the new WA7tp vacuum tube power supply

Building on the foundation of our multi-award winning WA7 Fireflies. The new WA7d adds optical (Toslink) digital input for expanded sources compatibility. Optical output is commonly found on Digital Audio players, CD/DVD players, XBOX, PS3, PS4 and on some TVs. The addition of optical input allows the WA7d to operate as a DAC for those devices, utilizing the advanced internal 32 bit digital to analog converter (DAC) for an improved sound.

WA7d Fireflies retains the same high-performance TI PCM5102A DAC chip and amplifier section as the WA7. The asynchronous USB 2.0 DAC is capable of decoding up to 32-bit/192kHz sample rates. A pair of 6C45 triode tubes acts as both driver and power in a single-ended Class-A design with transformer coupled outputs. An unbalanced RCA input allows for analog sources such as a turntable (with Phono stage) to be used with the WA7d Fireflies. There are no semiconductors used in the entire amplification path.

To maintain a small footprint and silent operation, we housed the custom built toroidal transformer in an external chassis. Every part was carefully chosen or custom built to deliver the best in audio performance. No matter which model you choose, WA7 or WA7d Fireflies will deliver many years of musical pleasure.

WA7d Fireflies Due Owner's Manual (PDF) pdf-icon

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

USB drivers for Windows XP/Vista/7/8 usb logo

USB drivers for Windows 10 usb logo

LIMITED TIME SPECIAL (was $999): $799* / $1399**

Black is not available.

* 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.

☐ * International shipping will be invoiced + 3% transaction fee.

What's in the box? 1 unit of WA7d 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.

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

Tubes are matched in a WA7d Fireflies for the best results.

Upgrade tubes 2: Reflector brand 6C45 NOS matched pair, $55

Tubes are matched in a WA7d 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 simplify form

The USB input supports up to 32/192k high-res playback. The new WA7d adds optical (Toslink) digital input for expanded sources compatibility.

The WA7p 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 and WA7d 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 new WA7tp (vacuum tubes PSU) would improve the overall sound quality of our award-winning WA7d Fireflies. You should notice, enhanced the stereo separation, smoother treble, more air, more effortless sound.

WA7d 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.


  • Single-ended, class-A, transformers output
  • Linear external high-performance power supply (remote-controlled power switching)
  • Two 6C45 driver/power tubes
  • C-Media 6631A USB chip
  • TI PCM5102A 32-bit DAC chip
  • Headphones impedance : 8-600 Ohms
  • Input impedance: 100 Kilo-Ohms
  • Sampling rate: up to 32-Bit, 192kHz
  • Inputs: 1 Optical (TOSLINK), 1 Asynchronous USB2.0, 1 RCA
  • Outputs: 1 1/4" and 1 1/8" headphone outputs
  • 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
    WA7p PSU - 2.8 lbs / 1.4kg
    WA7tp PSU - 9.4 lbs / 4.3kg


  • Handmade output transformer with Nickel Alloy core
  • 32-Bit, 192kHz 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 Optical input, USB input, and RCA input
  • All-aluminum chassis with no screws visible from any viewing angles
  • High clarity tube protection glass
  • Multi-layer military grade PCBs
  • Customized driver for Windows Vista/XP/7/8
  • USB Audio Class 2.0 is natively supported by Apple OS X version 10.6.4 and above without installing driver