Woo Audio WA7 “Fireflies”

Our Rating

“I have found that all ugly things are made by those who strive to make something beautiful, and that all beautiful things are made by those who strive to make something useful.”

~ Oscar Wilde 

It is a rare occasion when a component comes along that just makes sense. And the WA7 “Fireflies” does just that.

The WA7 is a combination headphone amplifier and 32bit/196kHz digital-to-analog convertor (DAC). It is the personal audio product I’ve been waiting for. Simplicity without sonic compromise, the grand promise of digital. At-home personal audio at its finest; just place the WA7 on desk, plug in USB, plug in headphones, watch tubes glow, and listen. And what you hear is the music, not the machine. It also happens to be one of the most beautiful looking audio products I have ever seen.

We all know, or suspect, that to turn people on to the benefits of better sounding audio, products should easily integrate into the everyday lifestyle.  No extra knowledge required. This is why Amarra works; it looks and acts just like iTunes. This is why headphones work; they don’t need dedicated space and they are already accepted into mainstream society. And with the WA7, Woo Audio succeeded in not only making a product that is useful to anyone with a pair of headphones and a computer, but one that performs sonic wonders in such a simple, yet praiseworthy design. The WA7 is a High End personal audio component that could easily make its way onto the desk of any modern day music listener, audiophile or not.

The first question is to ask why you would need an external DAC in the first place. At the most basic level a DAC (digital-analog-converter) does exactly what its name implies; it converts digital information into an analog signal. This analog electronic signal is the information that the amp, headphones, or speaker will use to produce sound. Whenever you listen to digital music, a DAC is being used somewhere in the chain. But computers and other digital sources contain quite low quality DAC’s, and for sonic purposes these are mostly awful. A standalone DAC will bypass subpar soundcards in a computer or device and do the converting themselves. The better the DAC, the better the conversion. And with better digital conversion, a more accurate reproduction of the original sound can be produced.

Now comes the question of why you would need a headphone amp. Basically, a headphone amp amplifies the incoming signal from the source and sends it out to the headphones. A headphone amp is mainly concerned with power, impedance, and signal quality. Audiophile headphones need be driven with enough power to minimize distortion and noise levels in order to maximize sonic fidelity, and this requires much more power than your iPhone or computer output can typically provide. A headphone amp will also have an output impedance to correctly match the requirements of the given pair of headphones (the WA7 has both low and high impedance options). Remember, a headphone amplifier will also impart, to varying degrees, its own colorations upon the reproduced sound.

Of course, you can use an external DAC and connect it to an external headphone amp to achieve amazing sonic results. But so doing introduces extra elements and further complicates an already complicated process. And this is exactly why an Amp/DAC combo, like the WA7, is desirable; it is an entire audiophile chain, save the source and the headphones, in one compact unit.

The next question you may ask is why you would need a $1000 combo Amp/DAC, and the simple answer is that you don’t, it just depends on what you are looking for. There are many impressive USB combo Amp/DAC’s on the market today (you might even say that the sub-$500 market of portable USB DAC’s is oversaturated). The ALO Pan Am, the Meridian Explorer, the Centrance DACport, and the Dragonfly come quickly to mind. These products can produce impressive sound, but they all have limitations. Of course, these compromises mainly concern price range and the need for portability. Not being portable, the WA7 doesn’t have to make these same sacrifices. One example is the WA7’s custom built, dedicated power supply that significantly reduces excess noise coming through the signal path. The sonic benefits are improved dynamics, a quiet background, and more controlled low end information; which the WA7 has in spades.


The WA7 is part of the personal audio revolution to provide a “High End” sonic experience through headphones. And when I say “High End” I do not affix a price tag to the declaration, although due to the bastardization of the field one immediately connects the two. Instead, I use the designation to infer that a product produces, or even hints at, the highest quality of sonic reproduction possible. High sound quality, not high prices. And only recently have personal audio products, such as the Audeze LCD3’s (review to come), begun to transform and shatter the limitations that once confined headphone playback.

For over 10 years, Woo Audio has been making great sounding, tube-based headphone amplifiers such as the WA2, WA6se, and the WA22. Recently, Woo released their first standalone DAC, the WDS-1, and it also lives up to the companies high quality standards of sound and performance.

Woo Audio is a family operation, begun by Jack Woo and his father and is based out of Queens, NY. The concept for the WA7 “Fireflies” was floating around Jack Woo’s mind for over three years time. He wanted to develop a product that married the sonic merits of the inspiring Woo Audio amps and DAC, and tuck them into a visually appealing compact unit; a design that would seamlessly integrate into the life of an everyday music listener (not just them crazy audiophiles).

The WA7 is simplicity at its finest, with tubes. The design is modern, elegant, and highly functional. Place this sturdy, nine-pound cube on your desk and you will be proud. An all-aluminum, screw-hole-free chassis and the thick block of solid glass on top, which protects the tubes from harms way, would never look out of place next to a MacBook Pro or other modern devices; it is that sexy. Although the dimensions are small and compact, this is not a “portable” unit by any means. And keeping you company on the subway or the plane may be the only thing the WA7 can’t do.

Driven by a pair of 6C45 tubes, the WA7 has enough power and sensitivity to drive any pair of headphones you will ever own (save electrostatic), with an impedance switch to match.  The WA7 comfortably drove my Audeze LCD3’s, a headphone that requires a good amount of power to work its finest magic. I used the stock tubes entirely for my listening analysis. There are not many upgradable tube options here, this is not a “tube rolling” device, but Woo Audio does offer a pair of Electro Harmonix 6C45 with gold plated pins for an extra $100. Although I haven’t had the chance to try them as of yet, I’ve been told they impart a slight openness to the sound. These may be of interest if you own “warm sounding” headphones or mostly listen to recordings that benefit from a more spacious sound (read: live, Jazz, or Orchestral music). But, on these types of recordings I found the stock tubes to deliver all the goods without restraint.

Once I received the unit, it took about ten minutes from opening the box to play mode. Set up was cake; place the tubes in their sockets, carefully put the glass top in place, connect the external power supply, and flip the switch on the back. To use a computer to source your music, connect a standard USB 2 chord directly to the WA7 and change your output setting on the computer. The internal DAC is native to Apple computers, so the device should register when you connect the unit and will show up as “Speaker” in your output settings. The desired input (or output, I’ll get to this later) and impedance (high or low) are controlled with switches located on the back of the unit while volume is controlled with a large dial on the front. You can easily hook up an iPhone or iPad (or really any device) to the WA7, but you will need to use the RCA inputs via a ¼”-to-RCA connector.

I should not forget to mention that the WA7 allows the RCA connections to be used as either inputs or outputs. Meaning: You can use an external DAC or other source to feed sound to the headphone amp or use the WA7 itself as a standalone DAC, like hooking up the WA7 to the pair of active speakers already sitting on your desk. The WA7 also has a dedicated 1/8” input for in-ear monitors (IEM) along with the standard 1/4” input.

My listening focused on using a MacBook Pro running Amarra (and iTunes) and the Audeze LCD3, but I also sourced CD’s and LP’s through the RCA inputs. One of the benefits of the WA7’s internal DAC is that it is capable of 32-bit/192kHz high resolution playback via standard USB 2. This means you are able to get the highest fidelity playback available (most combo DAC/Amps only go to 24/96). So, even if you aren’t already deep into high resolution audio, it’s nice to know that the option is available. Remember, you must use dedicated software, such as Amarra, to play such high resolution files from your computer source.


The WA7 has that warm and romantic tube sound I was hoping for, but never lacking detail. The WA7 is not a microscope, it makes music. One thing I enjoyed is that the sonic quality of most modern recordings (read: bright and over compressed) benefited from the WA7. The sound of the WA7 is relaxed and inviting, allowing you to easily slip into the music.

The first thing you notice is the dead quiet background. From the first bars on “Chan Chan,” from Buena Vista All Stars [24/96kHz HDtracks], I was struck at how effortless the sound was being presented. On Buena Vista All Stars, the soundstage was wide open and the air surrounding the musicians easily captured. I was able to turn the volume up without any distortion, noise, or corruption.  This recording is not “flat” sounding by any means, and the WA7 allowed the liveliness to come through unaffected. The WA7 handles dynamic information like a champion and listening to Coltrane’s self titled 1962 LP, the entire band sounded fierce and explosive – as they should.

When it comes to tone, the WA7 is lovely, with all the warmth a tube driven design can deliver. On Beck’s lonesome masterpiece, Sea Change [24/96 HDtracks], the sound was full-bodied, rich, and harmonically dense. On Buena Vista All Stars, the acoustic instrumentation was presented with a natural tone; the drums never sounded thin or lacking sufficient body. Bass through the WA7 is deep and controlled. On D’Angelo’s soul masterpiece, Voodoo, the bass was incredible and on “Untitled (How Does It Feel)”, it was focused and never blown out.

Vocals through the WA7 are stunning. On “Polly” from Nirvana’s Nevermind [24/96kHz, HDtracks], Kurt Cobain’s voice is presented with true authority; allowing you to get lost in his delivery and rough tone. Likewise, listening to the Beach Boys epic masterpiece, Pet Sounds [24/96, HDtracks], the luscious vocal harmonies are rendered beautifully and with enough detail to pick out individual voices. Using a WAV file of the Mercury Living Presence recording of Janos Starker performing Bach’s Suites for Solo Cello  [Mercury SR- 90001], a realistic image of the solo cello was heard; something hard to replicate with headphones (the cello can easily sound lumpy, with its delicate attack lost in the overtones of preceding notes and passages). The WA7 was able to reproduce the gritty and rich tones of the cello, as well as the high frequency harmonics resonating off the bow.

Listening to Radiohead’s Ok Computer and Squarepusher’s Ultravisitor, I was floored by the amount of detail I was hearing. I was able hear deep into the soundstage. Subtle dynamic information and instrument placement came through and was never glossed over. When I compared the WA7 to expensive standalone DAC’s, the WA7 held its own. Although there were subtle differences to be heard in terms of timing and micro-detail, the comparisons proved that the WA7 does not impart an analytical or overly “digital” effect to the sonic presentation; the way some DAC’s have a tendency to sound. My favorite sounding DAC’s are ones that sound like music, not microscopes, and the WA7 sounds like music.

Headphone playback is naturally direct because you are actually placed “inside” the soundstage. Therefore, it is far too easy for the sound coming through the headphones to sound like a fragmented sonic image. But, like the Audeze LCD3, the WA7 allows you to the experience the magic captured within a recording and not just the notes. Translating this information is the most crucial step in personal audio playback, because capturing the “spirit” within a recording is one of the most desired goals, if not the most, on the road to that illusive absolute listening experience.

The WA7 will most likely be the first thing I recommend to anyone asking my advice about high quality personal audio playback. This is the kind of component that makes audio so exciting. Is it the be-all end-all of personal audio? Of course not, nothing is. But inside the WA7 is every option you need to fully achieve realized, high resolution sound (save the headphones and source). Priced at $999, the WA7 is practically a steal in terms of sound quality and physical presentation. Most importantly, the WA7 is an uncomplicated playback design with breathtaking sonic ability. If you are in the market for such an item, there should be no hesitation here. The only real question is whether to get it in silver or black, because both look awesome.

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The Breakdown

Joseph Weiss is a musician, recording engineer, and composer. He is a vinyl monster, has a weakness for tubes, and believes that you should always trust your own ears.

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