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Woo Audio WA7d Fireflies

Woo Audio WA7d Fireflies

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Powerful, Compact, Complete

The Woo Audio WA7d Fireflies Duo is an all-vacuum-tube, transformer-coupled headphone amplifier with a built-in USB DAC. It all comes packed in a beautiful aluminum chassis and high-clarity glass block with a minimal desktop footprint. Long story short, it’s one of the best-sounding, best-looking, and most versatile DAC/amp combos on the market.

Note: At checkout, choose the WA7d in black or silver and 110V or 220V. The base price is for the WA7p solid-state power supply, and for an additional $600, you can opt for the WA7tp vacuum-tube power supply. Shipping is not available for members in Australia and New Zealand.

Woo Audio WA7d Fireflies
Woo Audio WA7d Fireflies
Woo Audio WA7d Fireflies
Woo Audio WA7d Fireflies

Artistic Design & Quality Sound

This isn't just an incredible DAC/amp—it's also a work of art. Every aspect of the WA7d Fireflies Duo was designed for sound quality and aesthetic pleasure. It’s handmade with its tubes encased in a solid slab of glass for tube protection, chassis dampening, and a striking visual experience. The maximum power output to headphones is 1W at 32 ohms, and the distortion is less than 0.03 percent. Combine these features and you get a silky-smooth sound in a very attractive package.

Woo Audio WA7d Fireflies

Function & Versatility

The WA7d Fireflies Duo is immensely flexible with multiple inputs: optical (TOSLINK), asynchronous USB, and stereo RCA. Use the optical input to connect to your DVD/Blu-ray player, XBOX/PS3 game system, or other digital sources. The USB input is best for computer audio to enjoy streaming music services such as Spotify, Apple Music, and TIDAL. For those spinning vinyl, connect your favorite phono preamp to WA7d's RCA input to enjoy your records collection. There’s a ¼-inch output for full-size headphones and an ⅛-inch output for IEMs. Another important feature is a rear-facing impedance switch, which you can toggle to synergize with everything from sensitive IEMs to power-hungry dynamics and planar magnetics. To keep this amplifier small while isolating the audio circuit from electromagnetic interference, the WA7d has a separate power supply (choose solid state or tube).

Woo Audio WA7d Fireflies
Woo Audio WA7d Fireflies

The Next Level

At checkout, you can choose the solid-state power supply or upgrade to the WA7tp tube power supply. The WA7tp is a high-performance linear power supply utilizing a pair of 12AU7/5963 tubes as rectifiers, bringing you enhanced stereo separation and smoother treble. For a final touch, the WA7tp features the same solid construction as the WA7d, ensuring both long-lasting durability and well-matched aesthetics.

Woo Audio WA7d Fireflies


  • Up to 32bit, 192kHz high-resolution playback
  • Ultra-low jitter USB 2.0 runs on asynchronous mode
  • High- and low-impedance output via toggle switch on back panel
  • Open load protection will automatically engage to prevent the amp from damage when no headphones are plugged in
  • Multifunctional switch for USB, optical (TOSLINK), and RCA input
  • All-aluminum chassis with no screws from any viewing angles
  • High-clarity glass block for tube protection and chassis dampening
  • Multi-layer military grade PCBs
  • Customized audio driver for Windows XP/Vista/7/8/10; Win 10 Creators Edition supports USB 2 natively (recommended)
  • USB Audio Class 2.0 is natively supported by Apple, macOS Leopard, and above

Model Options

WA7d – black
WA7d – silver
WA7p solid-state power supply (+ $600)


WA7d Specifications*

  • Single-ended, Class-A, transformers output
  • Linear, external, high-performance, solid-state power supply unit
  • Two 6C45 driver/power tubes
  • C-Media 6631A USB controller
  • Texas Instrument (TI) PCM5102A 32-bit DAC chip
  • Sampling rate: up to 32 bit, 192 kHz
  • Headphones impedance : 8–600 ohms
  • Input impedance: 100 kohms
  • Inputs: 1 asynchronous USB 2.0, 1 RCA, 1 optical TOSLINK
  • Outputs: 1 1/4" and 1 1/8" output
  • Max output: Approx. 1 watt at 32 ohms
  • Frequency response: 11 Hz–27 kHz, +/-0.5 dB
  • Distortion: <0.03%
  • S/N: 95dB
  • Power consumption: 25W max
  • Mains supply: 100–120V, 220–240V, 50/60 Hz (factory preset)
  • Finish: Anodized aluminum, available in black or silver color
  • DC cord length: 4 ft (1.3 m)
  • WA7d dimensions: 4.8 x 4.8 x 5.1 in (12.2 x 12.2 x 13 cm) with glass
  • PSU dimensions: 7 x 3.5 x 2.2 in (17.8 x 8.9 x 5.6 cm)
  • Weight: Amp: 5.3 lbs (2.4 kg); glass: 3.3 lbs (1.5 kg)
  • PSU weight: 2.8 lbs (1.4 kg)

WA7tp Specifications*

  • WA7tp vacuum-tube power supply
  • Matched pair 12AU7/5963 tubes as rectifiers
  • Anodized aluminum body with no visible screws
  • High-clarity glass block for tube protection and chassis dampening
  • Multi-layer military grade PCBs
  • DC cord length: 1 ft (0.3 m)
  • Mains supply: 100–120V, 220–240V, 50/60 Hz (factory preset)
  • Power consumption: 25 W max
  • WA7tp dimensions: 4.8 x 4.8 x 5.1 in (12.19 x 12.19 x 12.95 cm)
  • Weight: 9.4 lbs (4.3 kg)

* Subject to change/improve without notice


All orders will be shipped by Massdrop.

Estimated ship date is Nov 10, 2017 PT.

After the drop ends, payment will be collected and the group’s order will be submitted to the vendor up front, making all sales final. Check the discussion page for updates on your order.

Recent Activity

A salesman once told me “ not every headphones excel with tube amps “ . And he also said “ you have to try your own pair with the tube amp before buying it ”. He was absolutely right. I met him when I went to his company in order to try some headphones, dacs, amps , and IEMs. I have a pair of M1060 and brought them with me. I tried a bunch of headphones like Focal Elear, Grado ,HiFiMan Susvara,Edition X and Sundara , along with my M1060 , on different dac/amps and on different Woo Audio tube amps including WA3, WA7, WA8 Eclipse, and WA5 (which costs 5,700$). Immediately I realized that not every headphones are designed for tube amps. For instance , the Susvara ( 6000$ worth of headphones ) didn’t impress me on tube amps, even with the WA5, but on a good dac/amp that’s a different story. I tried my M1060 on all those tube amps and let me tell you that the result was amazing. The WA5 drives a lot of power that may literally break your headphones but the sound is wonderful, a bit tense but still. Pairing my headpphones With WA7 came with outstanding results. The sound was worm and beautiful specially the trebles. I listened to a lot Jazz and Classics and for the first time in my life I feel I’m about to cry for the music!. WA3 was fine but not even close to WA7. The WA8 Eclipse on the other hand was really really amazing, superb and without a doubt the best portable tube amp out there. Long story short, i had to try different headphones on different tube amps to make my mind. And while headphones won’t do well on some tube amps, they may have a better sound on other lower ones. For example, the Sundara sounded better on WA7 than on WA5. That doesn’t mean WA7 is better than WA5.