Contact Us

Use the form on the right to send us an email.


123 Street Avenue, City Town, 99999

(123) 555-6789


You can set your address, phone number, email and site description in the settings tab.
Link to read me page with more information.


WA7d Fireflies Duo Headphone Amplifier/DAC

Screen Shot 2018-06-07 at 5.02.45 PM.jpg
Screen Shot 2018-06-07 at 5.02.45 PM.jpg

WA7d Fireflies Duo Headphone Amplifier/DAC

from 799.00
  • Sale! $799.00 [Reg. $999.00]

  • Sale! $1,399.00 [Reg. $1,599.00 with Tube Power Supply]

  • Limited stock, ships in 1–2 days

  • Add 3% for international orders



The Woo Audio WA7d "Fireflies Duo" Amp/DAC is a combination of high performance vacuum tube headphone amplifier with a built-in USB Digital-to-Analog Converter. To accommodate different system setup needs, "Fireflies Duo" adds optical TOSLINK input. WA7d 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 signal path. The D/A converter is designed to be capable of up to 32-bit/192k 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, an external 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 outputting up to 1w of power to drive almost any demanding audiophile headphones.

 Shown with WA7tp upgrade

Shown with WA7tp upgrade

  • Tubes: 6C45 driver/power 2, 12AU7 rectifier x 2 with WA7tp upgrade
  • Single-ended Triode, Class-A, Transformer-couple
  • Texas Instruments 32 bit, 192kHz DAC
  • Asynchronous USB compatible with PC, Mac, Android and iOS devices (with Apple CCK or Android OTG adapter)
  • Optical (TOSLINK) Input x 1, RCA analog Input x 1
  • 1/4" (6.3mm) stereo headphone output (8–600 Ohms)
  • 1/8” (3.5mm) stereo headphone output (for ultra-sensitive IEMs )
  • Linear solid state power supply OR upgrade to WA7tp (tube power supply)
  • Anodized aluminum chassis, available in black or silver
  • Self-biasing with compatible tubes [chart]
  • Dimensions: WA7 amp with glass: 5 ¼" (H) x 4.8" (W) x 6" (D) 8.6 lbs. with glass, Solid state power supply: 2.2" (H) x 3.5" W x 7" (D) 2.8 lbs., WA7tp with glass: 5 ¼" (H) x 4.8" (W) x 6" (D) 9.4 lbs.
  • Global voltage (100v–240v) without a converter


 *Specifications and appearance are subject to change for improvement without notice.

*Specifications and appearance are subject to change for improvement without notice.


  • Quick start guide
  • WA7d Fireflies Duo x 1
  • SOVTEK 6C45 vacuum tube x 2
  • Anti-slip glass pads x 4
  • Solid state power supply x 1 with 4ft. DC cord x 1 [not included, replaced by WA7tp with upgrade]
  • Standard USB A to B cable x 1
  • U.S. style AC power cord


  • WA7tp (tube power supply) x 1 with 1ft. DC cord x 1
  • 12AU7 / 5963 vacuum tube x 2
  • Anti-slip glass pads x 4

*Audio cables are not included

In the box


Amplifier Tube Upgrade (WA7d)


Power Supply Tube Upgrade 1 (WA7tp)

Power Supply Tube Upgrade 2 (WA7tp)

Comments and Reviews