Digs the Woo Audio WA7 Fireflies

A syndicated article from by amos barnett, warren chi, michael liang, kevin venable & ethan wolf

Remember your first kiss, a new puppy wagging its tail at you, the opening notes of your favorite song, the slightly bitter yet sweet taste of an exquisite French marmalade like St. Dalfour? Okay, maybe Warren is the only one with that kind of passion for marmalade, but you get the picture….

NOTE: Warren has a thing for marmalade. Nevermind, it’s not important.

We’re smitten.

Now that we’ve discarded any semblance of suspense, let us tell you why you’ll be smitten too. From top to bottom, inside and out, the WA7 from Woo Audio is an embodiment of beauty and poise. It is the Grace Kelly of headphone amplifiers. Even after months of use, it remains an object of our machine love (and lust on occasion).

Design & Build

To ignore the aesthetics of the WA7 Fireflies would be folly, begging to be trampled by the elephant in the room. It is absolutely and stunningly gorgeous, nearly beyond-words. There are few curves to speak of, but this fetching and foxy little box is audiophile porn at its very best. Some of us blush when staring at it too long, others stare unabashed, but be warned it will be stared at, as the WA7 easily becomes the focal point of any desk it is on.

The WA7 Fireflies is available in two shades of gray: black and silver. But regardless of what tone you fancy, the WA7’s most distinctive feature is its optically-clear glass top, which is frankly, a stroke of sheer genius. While tube glows are spellbinding, the Victorian/Steampunk-ish tube guards found on most tube amps tends to clash with modern desktops. The WA7’s glass top doesn’t. And in fitting that glass block perfectly flush to the amp’s body, Woo Audio has tied everything together in a way that is simply elegant to behold.

Accented by a lone, low-profile volume knob – finely ridged for our pleasure – and seated nearly dead-center, the WA7 Fireflies maintains its exceptionally clean facade effortlessly. Only two flush mount jacks in the bottom-right (which are necessary) serve to detract from what is otherwise a perfect example of visual minimalism. Even then, the jacks are balanced out by a laser engraved moniker on the opposite side.

Overall, the WA7 is a smooth, seamless and screwless wonder – having been machined from a solid block of aluminum. But don’t think for a minute that this amp is lightweight in any way. Even without the separate power supply, the amp weighs in at 8.6 pounds (3.9 kg) sans tubes. That might not seem very heavy, but I can assure you that you would never expect that from something that is only 5 cubic inches.

Functionality & Usability

Visual superlatives aside, the WA7 is wholly deserving of its reputation as one of the most desirable products to debut this year, due to its rich and versatile feature set.

It sports an integrated 32-Bit/192kHz USB DAC which is – in all probability – complete overkill for most music collections. It drives single-ended headphones and IEMs from 8 Ohms to 600 Ohms using two 6C45 tubes, which are even rollable to a limited extent. And user-selectable settings for both low and high impedance headphones allow you to tailor the WA7’s output for your specific needs.

This brings us to the single best feature of the WA7: it plays your game, however you want to play it.

Do you listen via IEMs? One of the WA7’s most seductive features is the secondary 3.5mm TRS jack on the front panel. Specifically-engineered for amplifying high-efficiency units, it can drive IEMs to ear-splitting levels without distortion. This appeals to Warren’s sensibilities as he has quite a few IEMs, with more being added to his collection on a monthly basis. In many ways, some of today’s greatest advancements in personal fidelity are happening in the micro-transducer world. And in looking ever forward, Woo Audio has realized that fact on a very practical level.

Already have a favorite DAC? Should you find the built-in DAC not to your liking, you can easily bypass it. Just swap in another DAC using the WA7’s rear RCA inputs, and flip a switch. We’ve found that a CEntrance DACport LX, HRT MicroStreamer, or JDS Labs ODAC fits the bill nicely while remaining well out of sight.

Another use of the RCA input that Kevin found especially well-suited to his system is adding an analog front end, like a turntable or reel-to-reel tape player. If you have a CD or multi-player that you love, this input will work wonderfully with that as well.

Not in the mood for tubes today? Need a quick fix and don’t want to wait for the tubes to warm-up? You can likewise bypass the amp and use the WA7 as a standalone DAC, paired with another amp from your collection. With another flick of a switch, the RCA input jacks turn into outputs instead. In fact, you won’t even need to power up the amp since the DAC can be bus-powered solely via USB.

We do enjoy the WA7’s overall presentation mind you, so we are not suggesting any need to use another DAC or amplifier. Our point is simply to illustrate that it doesn’t rob you of options the way an integrated DAC/amp typically would. Speaking of the WA7’s presentation…

Sound Quality

Warren Chi: Please note that all of the following impressions were gathered on a WA7 Fireflies upgraded with a matched pair of Electro Harmonix 6C45 tubes with gold-plated pins, obtained directly from Woo Audio. The stock tubes, which are a matched pair of Sovtek 6C45 tubes, were also available. However, they were not used for impression gathering, mainly because I found the Electro Harmonix upgrades far superior in terms of sonic performance.

Before we get into what you’ll hear from the WA7, lets take a moment to talk about what you WON’T hear from it. Noise. Amazingly, this little gem of an amp has one of darkest backgrounds I have ever heard – or not heard rather. It is absolutely pitch black. Honestly, you’ll get more sonic satisfaction trying to hear skin cells grow. But pump in some music, and the WA7 rises from its dead silence with astonishing presence.

Common with tube amplification, the WA7 delivers an impressively weighted low end. You’ll find your music solidly anchored, with just enough warmth to verify its tube amp credentials, but nowhere near enough mugginess that it stifles the senses. In omitting any and all excessive warmth, the WA7 presents us with uncharacteristically linear bass response, clean beyond my expectations, and full of punch and dynamics.

With Madeon’s “Icarus (Radio Edit)”, the WA7 deftly rendered its sawtoothed bass lines and electro kicks as individual voices (via a pair of Ultimate Ears 900 IEMs), while preserving the sonic distictiveness of each element in the process. And thanks to the aforementioned punch and dynamic prowess, “Icarus’s” subtle stutters formed into well-timed cuts instead of smearing together into a smattering of underwhelming level drops.

But competent mid-bass isn’t exactly a difficult proposition these days. Curious to hear how low it can go, I decided to taunt the WA7. Stupid move. Sub-bass performance is no less impressive with the WA7 extending well down below my detection threshold. In its response, the WA7 put me on notice. With Trentemøller’s Remix of Röyksopp’s “What Else Is There?”, piped into a Denon AH-D7000, I found myself slowly and repeatedly violated by the ambient sub-bass. The WA7 remained adamant. It was not about to apologize for lackluster sub-bass any time soon. Point taken, moving on.

BONUS TIP: If you’re a basshead, and crave even more sub-bass, reach back and toggle the WA7 into Hi-Z mode. You’ll get a slight but perceptible boost at the bottom end. You’re welcome!

Transitioning into the lower mids, I witnessed the WA7 culling the very essence of my music, seemingly from the ether. That gentle warmth in the bass gives way to a sparkling sea of details like fireflies in the night. With “A Change Is Gonna Come”, I found Mr. Sam Cooke as sublime and soulful as he’s ever been. As various orchestra members sauntered onto the soundstage, the air filled with a natural and musical sweetness, with layers and layers of accompaniment slowly playing musical chairs before me. My life settled into a three-minute romance, reminiscent of a more pastoral time that exists only in my imagination… all through a humble pair of AKG K240 Studios no less!

Like water seeking its own level, the WA7’s lower mids flow into the upper mids seamlessly. They are forward, engaging and desk-drummingly lively with a sense of depth that borders on being holographic at times. Listening to The Judybats’s “Native Son”, through an Etymotic ER-4PT, I was caught unawares by the pleasing harmonics coming off the various snare, cymbal and hat hits. The absence of distortion or congestion kept each sonic detail delightfully pristine, whole and non-fatiguing.

The highs pick up right where the upper mids leave off, and what was once a sense of depth, is now an airy expanse. Where there were once harmonics, there is now that most elusive of audio qualities – sonic fairy dust. And going where no ears have gone before, the uppermost highs now leave the confines of our hearing range, gradually tapering off into the infinite. No need to believe my fanciful tales. Check out Bob Acri’s “Watch What Happens” through a pair of Ultimate Ears 700 IEMs and hear for yourself. Behold the splendor of Ed Thigpen’s stick and brush work wisping into the gossamer night.

Those of you with a sensitivity to treble will be happy to learn that the WA7 seems to act as a sibilance filter. It was never strident, nor shouty, and it was able to accomplish this feat without casting a veil of any kind. This was the case regardless of what track I played, or what headphones/IEMs I used.

As you might imagine, the WA7 scores high marks for both detail and separation. The WA7 does little to obscure the sonic minutiae of your music. For all of you detailheads out there, this means that the WA7 will likely not be the weak link in your signal chain. Proof positive comes in the form of “Ring Them Bells”, Sarah Jarosz’s cover of a timeless Dylan ballad. Piped through a Grado GR8, one of the few moving armature IEMs available today, each and every bit of bass, guitar, mandolin, slide guitar, dobro, fiddle, and vocal detail is retrieved effortlessly and served up with delicious clarity.

Likewise, psychoacoustics suffer little at the hands of this tube cube. The soundstage laid out by my K701 remains as wide as ever, with superb imaging characteristics to match. Relaxing with The B-52’s “Follow Your Bliss”, my imagination conjures up a daydream of the band spending a lazy afternoon, rehearsing in a dusty dance hall for that night’s gig.

Finally, we come to one of the WA7’s more peculiar features – its subtle dynamics. I say subtle because rather than charging into you, the WA7 plays a finesse game made possible by its background noise (or lack thereof). It may never truly knock you down, but you better believe it’s going to score. Simply put, the dynamics remain absolutely breathtaking in their poise, while being unrelentingly exhilarating as befitting the music.

John Williams’s “Here They Come!” from Star Wars provides us with a visceral point of reference. If you’re not familiar with this particular theme by name, it’s the scene where Obi-Wan has just died, and the Millenium Falcon is under attack by a squadron of TIE fighters as it tries desperately to escape the Death Star. In pairing the WA7 with a Sennheiser HD 650, a pair of headphones that tends to eschew sonic clutter, we are subjected to every pang of gut-wrenching anxiety Williams saw fit to induce.

I am completely and utterly distraught. In so many ways, I desperately wanted the WA7 to be marginally good. Why couldn’t it be somewhat admirable or even simply adequate? What was the technical reason why it couldn’t be colored in all the wrong ways, instead of all the right ways? Why didn’t they leave it underpowered and underwhelming to better fit my mental image of a Woo-lite amp? And really, would it have KILLED them to slip in a little noise or distortion here and there?

We have an old saying where I come from (i.e., whereby we caution noobs about the perils of overspending on audio. “Sorry about your wallet,” we jest sadistically. What a cruel joke that I should now find myself caught up in this predicament. From all that I have learned about the WA7 Fireflies, there is one inescapable personal truth that I could not deny: I had to have it.

Kevin Venable: Please note that all the following impressions are made with the stock Sovtek 6C45 tubes as I do not have the Electro Harmonix upgrade. That being said I do look forward to trying them and reserve the right to make a follow up post to this review after I do so.

The first time I heard the WA7 Fireflies was at the LA Head-Fi meet. Warren had brought it along but as his laptop was used in another system I offered the use of my MacBook Pro. We hooked it up and I hit play on a 24-bit version of Slow from Depeche Mode’s Delta Machine that I had just been listening to on another much more expensive system a table over. The impact of that song through the WA7 was so close to the previous (and much more expensive) system that I immediately thought I really need to get this home. I didn’t know at the time that it’s sound, feature set and footprint would make it the logical fit into my system. After months of research and thinking I ordered one of my own.

Since my listening habits are a bit different than a lot of people who primarily listen to headphones, a description of the system from which most of my impressions are gathered is in order, as system synergy is key. I mainly listen to vinyl when relaxing with music and yet listen to both Hi-Rez downloads and online streaming services while working or chatting online. So that versatility was paramount in choosing an amp/DAC combo. My vinyl rig is a VPI Traveler with a Denon DL-103 Cartridge connected to a Parasound zPhono USB with a WyWires Silver Phono cable. The phono preamp is connected to the WA7 with a WyWires Blue RCA interconnect cables. My MacBook Pro Retina is connected to the Fireflies with a WyWires LiteSpeed 2.0 Silver USB cable. Except where noted my listening impressions are from the analog front end.

Esperanza Spalding’s “Crowned and Kissed” comes sauntering out of my Sennheiser HD700s with a snap and swagger in the bassline that I have never heard before. Each notes placement and dynamics are easy transferred to the ear in a way that oozes groove. Esperanza’s voice is harmonically rich and the horn lines especially the fiery trombone solos blaze above the rhythm sections foundation. Everything in this busy arrangement is easily isolated yet it is whole picture that is beautiful to behold! Perfectly balanced from foundation to embellishment. The WA7’s control and dynamic swing are sublime resulting in what the British call excellent PRaT; Pace, Rhythm and Timing. It is this that allows a piece of metal and glass to convey groove and let me tell you the WA7 Fireflies has groove in spades.

The first side of The Drum’s excellent LP, Contact, is an exercise in both finesse and force that is handled with aplomb. Subtle sounds swirl around your head in the highs and mids, as the low end shakes you while offering a significant foundation for the flights of fancy above. I was also surprised by the WA7’s adept handling of both the sub and mid bass that are so important to the electronic music that I love so much. Much more compelling though was it’s ability to handle the thunderous lows while still offering suppleness and texture throughout the low end. This album has been in high rotation around here and the WA7 presents it wonderfully especially through the my Sennheiser HD700 and the over-achieving KEF M500.

As important as the low end foundation is, music lives and breathes in the mid range. Fink’s Perfect Darkness, the title track of his 2011 Ninja Tune release, is breathy and sparse in composition. And yet, it sounds full and emotional rendered through the WA7. The acoustic guitars sparkle on top of the string pads as Fink’s voice beckons you into the dark. This is goosebump material from the WA7 driving the HD700.

Lee Morgan’s “Twice Around” off the 45 RPM reissue of Tomcat speaks authoritatively through the AKG K701 with harmonic complexity seeping from the horns. Morgan’s trumpet is a lively beast while Curtis Fuller’s trombone tone is revealed in all it’s breathy glory. I feel Jackie McClean’s sax is a little lean, though it still sings. McCoy Tyner plays superbly and the upper register of the piano sparkles through the crispness of Blakey’s hi-hats and ride cymbal. The cymbal work and 4 bar drum breaks in this song reveal the speed of the WA7 and K701 combination resulting in breakneck stops and starts and excellent definition on every stroke of the stick. They highs on the WA7 are wonderful; never too sharp or painful even with headphones that with some gear are noticeably piercing, including this K701 and the Sennheiser HD700.

“‘Round Midnight” from Ella Fitzgerald’s album Clap Hands, Here Comes Charlie in 24 bit 96 Khz played with Amarra Hi-Fi is beautiful, though I find Ella’s voice to lack a bit of the warmth and fullness that I have heard with other tube amps. The swing factor of the track is very high as the WA7 once again shows it’s superb handling of the leading edges of notes.

The crunch, anger, resentment and hope of Gemini Syndrome’s “Mourning Star” is abundant streamed via MOG out the IEM port into the HiFiMAN RE-400. The sound and usability of this output gives me a bit of consternation as I only own one set of IEMs and this port begs me to buy more.

Flipping two switches to return to the turntable and Hi-Z output for my HD700, the combination I have come to favor for most listening with the WA7, I drop the needle on what is probably my favorite track of the past year. Steven Wilson’s epic twelve-minute progressive rock masterpiece “Luminol” from his album The Raven that Refused to Sing and Other Stories is a work of finely crafted genius. Each instrument plays a role and by themselves are beautiful however it is the whole in which I revel in. The Woo Audio WA7 Fireflies just plays music here by getting out of the way and allowing me to wallow in the song and explore it fully. The song and the WA7 are very similar in that they both combine wonderful individual parts to create audio art.

Ethan Wolf: Please note that all of the following impressions are made using the Electro Harmonix 6C45 tubes with gold-plated pins, and not the stock Sovtek 6C45 tubes. 

First off, let me explain how the two tubes compare and contrast with each other. In my findings, the Electro Harmonix upgrade tubes proved to be a fuller, richer sound. Echoing what Warren has said, I would consider the upgrade tubes to be a necessary upgrade; it should not be missed. When using the Electro Harmonix tubes, the sound is warmer, more full of life, and overall, a more enjoyable listen.

Moving on, the WA7, proved to be my favorite piece of equipment I have purchased in my audio expenditures. My favorite thing about the WA7, is that all my headphones can be used with it, and sound fantastic with it. The bass on it, is warm and full of life. It is extended and punchy, with its PRaT at perfection. The WA7 never misses a beat, or even stumbles with it.

On the song “Money” by Pink Floyd, the bass never dares to leak into the mids, and it’s extremely detailed and airy. I wouldn’t fault the bass for anything, for such a compact and gorgeous looking amp/DAC, it’s stunning how this thing sounds (and looks)!

The midbass, while enjoying the song “Disco Infiltrator” by LCD Soundsystem is out-of-this-world tight and punchy. I’ll share a little story that happened just a second ago, while I was looking for a song to write the midbass about, I randomly clicked on Disco Infiltrator, wondering if it had prominent midbass in the song; upon hearing it in the song, I thought to myself, “does it really sound that good?”. Answering myself, yes, it does.

Now, onto the mids, which are like the bass and midbass, warm. I have to confess, if a headphone/amp/DAC is warm, I am bound to like it. Analytical audio pieces and I don’t get along too well, as I love to sit back and enjoy music. I loved that the WA7 allowed me to do this, as my previous amp/DAC, the O2/ODAC, was far too analytical and cold for me. But, I have to admit, it did sound fantastic for the $300 price tag. Alright, enough with the chit-chat, the WA7 presented beautiful, realistic mids. The midrange is not analytical in any way, and takes some of the edge off of some harsher songs and headphones.

Speaking of harsh songs, I tuned up the song, “Ghost” by Neutral Milk Hotel, now if anybody knows Jeff Mangum’s voice, it is not beautiful in a conventional way. However, the WA7 managed to turn his voice into a very nice one.

Onto some jazz, “Freddie Freeloader” by Miles Davis, the trumpet is full, detailed, and enjoyable. Nowhere does analytical pop into my mind, only sweet tunes.

The highs with the WA7, were no let down, with the song, “The Great Gig in The Sky” by Pink Floyd, are smooth and are pushed a little back. Doing this, allows for the highs to never sound piercing. They’re very detailed and warm, however, I would’ve preferred for them to be just a little more forward.

Furthermore, if you own a T50RP or any T50RP modifications, the WA7 is a must buy. My Paradox and WA7 combo is out of this world.

Amos Barnett: My first impressions of the WA7 using the stock tubes was of a slightly tubey mellowness. While I already find the Audeze LCD-3s to be mellow in their own way, with the WA7 they become a great relaxation tool. The WA7 didn’t seem to be making an effort to drive them – it wasn’t the mellowness of an under-performing amp, thankfully.

Switching to the Electro Harmonics Gold Pin 6C45s and the tubey mellowness was replaced with more directness and authority, while maining a touch of warmth in the bass, which matched well with both Audezes and Sennheiser’s HD-800s. In fact, the WA7 with the HD-800s became one of my favourite pairings. While the amp doesn’t quite keep up to the pace of my ALO Audio Studio Six, which has the ability to deliver amazing dynamics, it wasn’t so far behind that I felt wanting. Powering it through my PS Audio Power Plant Premier brought it closer, leaving on the in-built DAC as the bottleneck. Woo Audio plans to bring out a better tube power supply for it this year, which should bring about similar or better results for people who want to upgrade or spend more.

I am always wary of one-box DAC/amp solutions so I was pleasantly surprised at how listenable the WA7 was from its built-in DAC. I tend to be fairly sensitive to digititis in DACs, but the BB-based DAC wasn’t offending me, even with a high-res recording of a local jazz group, the Keishi Matsumoto Trio. Since the DAC is USB bus-powered, I decided to see if any improvement could be had with higher quality USB power and tried again with an Aurorasound USB Bus Power Pro. The slightly hard edges of notes were marginally softer and a little more detail was available than when using the power from my iMac, suggesting either my iMac or the DAC is more capable with power than expected.

Switching to a dedicated DAC revealed how much micro-detail was being lost by the in-built DAC. The finer details on note decay are missing as well as the subtle harmonics. Changing between different DACs the different characters in various designs were audibly apparent. A non-oversamplic Metrum Octave resulted in a sound that was too mellow overall. A DAC such as a Calyx 24/192 + Audiophilleo or the ultra-capable Resonessence Invicta made for a better match, the cooler, more “hi-fi” sound mating very nicely with the slightly warm WA7.

Overall, the sound strikes a perfect balance between easy listening and being detailed and dynamic, regardless of the headphones being used, with plenty of potential for better sound through external upgrades. Primarily though, I do feel it succeeds as an attractive (both figuratively and literally) “one-box” solution for the average person who is willing to spend around $1k.

Michael Liang: When I first saw the marketing materials for the Woo Audio WA7 Fireflies, I admit, it didn’t emotionally move me. Yes the WA7 looks unique and stands out from the array of headphone amps on the market, but I got the impressions of it being another “lifestyle” product – all looks and no go. At the last L.A. Head-Fi meet, I helped move Warren’s unit out of the packing and on to the listening table. My immediate reaction was “oh damn, this thing is HEAVY”. The weight of the WA7 caught me by surprise so it got my interest to further investigate.

For this review, I opted for a set up that is as elegant and clean as the WA7 Fireflies – 64GB iPad (128GB is also now available). Yes, the WA7 Fireflies’s 32-bit/192kHz DAC is iOS compatible with the help of Apple’s Lightning-to-USB adapter. Although iPads are limited to a maximum of 128GB of solid state storage for media, iOS offers ultra-low power consumption, is quiet, has ease-of-use, making the iPad an ideal music server.

One of my early concerns with the WA7 was will it be overly warm or lush sounding, as is common in tube amps. I am pleased to report that those concerns are no longer valid. Aside from a slight midrange forwardness, the WA7 is relatively neutral – this is on the stock Sovtek tubes.

Comparing the Woo to my old friend, Musical Fidelity X-Can v8 (Jan/Philips ECC88 tubes with upgraded Little Pinkie power supply), it is evident that the Woo isn’t playing in the mid-fi playground. There was plenty of depth in the music out of the Beyerdynamic T51p.

Sampling through the collection of headphones in my stable revealed that the WA7 does wonders on models with transparency and some emphasis on bass e.g. Sennheiser Momentum, Focal Spirit Classic, or the B&W P7. The Woo has plenty of gain to drive cans like MrSpeakers Alpha Dog, Beyerdynamic T1, and Sennheiser HD800 to adequate volume levels.

I think the stock Sovtek tubes does a fine job at giving the listener a taste of tubes smoothness without making the sound too soft. But swapping out the tubes for the optional Electro Harmonix gave the midrange more texture, and the bass response got a boost.

Only a year on the market, the Woo Audio WA7 is already very well reviewed by audio publications and owners. Manufactures will have to take notice that the days of black boxes with LEDs and knobs are numbered. We audio enthusiasts want good looks to go with great sound.


Warren Chi: By the way I’ve been waxing effusively this whole time, one might wonder if there is anything that I don’t like about the WA7 Fireflies? Why yes, there is! I am not a fan of the stock Sovtek tubes. Though relatively balanced, they’re somewhat dull and lifeless at the bottom, with thin and dry mids, and even thinner and somewhat brittle in the highs. They sound a little like death warmed over. I do not recommend them.

Instead, do youself a ginormous favor by opting for the Electro Harmonix gold-plated tubes that Woo Audio offers as a mere $100 upgrade. Consider it a required upgrade. And in doing so, re-factor the WA7’s cost at $1,099 right off the bat. Your lows take on a refined warmth, just enough to let you know that you are running tube amplification. Both lower and upper mids will be tonally rich with life-like timbres. And the highs truly open up.

And while I would not call it sub-par by any means, I found the WA7’s DAC stage to be too smooth for my liking at times – particularly for pieces of music where I crave textural detail. Again, it’s not bad by any means, but I did find my CEntrance DACport LX to be more enjoyable – or at the very least more detailed for some of my music.

Kevin Venable: While I don’t have quite the aversion to the stock tubes that Warren displays above I wonder if my thoughts that some female vocals and instruments, especially saxophones, are a bit lean at times could be fixed with the tube upgrade. This slight problem I have with the upper midrange is my only complaint sonically and I hope that is alleviated by the tube upgrade (which I currently have on order).

Functionally I wish the the RCA output was a separate set of jacks to allow pass through of both the DAC and my turntable possibly with volume control for a set of powered speakers. That is very likely asking too much from a DAC/AMP in this price range though.

Ethan Wolf: One of two caveats I want to point out with the WA7 is that the stock tubes are much worse than the upgraded Electro Harmonix tubes. The EH tubes presented a more warm and full presentation, for a more enjoyable and relaxing listen.

My second, is that the WA7 comes with no cables to speak of. For a $1,000 machine, I would have at least expected a power cord. I will let the lack of a USB cable slide, as not everyone will use the USB DAC. Luckily though, the power cord is simply a standard computer power cord. Most people are bound to have one of these lying around, though, I did not have one. As for the USB cable, you will need a USB Type B cord.

Amos Barnett: If I was to have a criticism, it might be the DAC, which isn’t up to the capabilities of the amp. But if it weren’t there, the WA7 wouldn’t be a one-box solution, which is what many non-enthusiasts want.

One potential issue with the amp is that the gain is set somewhat low, though in one respect this is a good thing, as it ensures the volume pot is used in the middle of its rotatation where it won’t have any channel imbalance. It wasn’t a problem to have the volume up high, but sources with a low power output can require the volume turned to maximum.

Michael Liang: Personally, I would like more UMPH from the amp. For me, one aspect that I think every great amp should have, is stunning dynamics. With the WA7, I was rewarded with a lot of finesse and refinement, but it lacked some of that surging impact that I’ve grown accustomed to from the recently reviewed Lehmann Audio Linear USB.


Back in the eighties, Sony released a line of audio electronics under the brand name My First Sony. Geared towards children, it leveraged Sony’s reputation, introduced the brand to a whole new generation of future consumers, and was phenomenally successful for a time. In many ways, the WA7 Fireflies should be considered just such a thing – a My First Woo.

If you’ve never taken a foray into tube amplification for your headphones, the WA7 is an excellent jumping off point. The sound is just tube-like enough to give you a satisfying taste of things to come. Tube rolling options are finite, and thus a simple and inexpensive proposition. And its rich feature set obviates the need for a separate USB DAC, leaving the WA7 Fireflies less of a drain on your wallet than you might think.

Already have an endgame headphone rig? Leave the WA7 Fireflies on your wishlist because it makes a brilliant centerpiece for your desktop or bedroom rig instead. Its Lilliputian footprint ensures that it fits right in with even the most diminutive of desks and nightstands. And if we’re to be honest, the sight of a silver WA7, paired with a MacBook or iPad, accented with a silver Woo Audio aluminum headphone stand, would be right at home in any contemporary museum.

As a parting thought, we’d like to leave you with a Matthew Sweet lyric, to sum up how we feel about the WA7:

I didn’t think I’d find you perfect in so many ways. But I’ve been waiting, waiting. And I want to have you.

And have it we did. As of this moment, five of us have purchased our WA7 units, and the sixth is on the fence. We guess you could call that a positive recommendation.


  1. One glaring problem, no matter how great this little amp happens to be.
    No balanced. Balanced under most conditions is s a greater improvement than going from a low to a high end amplifier.
    No balanced, and this buyer would not even consider this amp.

    • I strongly disagree with that. A lot of amps will sound “different” from their balanced output… some sound better, some worse, than their single-ended output (assuming they even have one). But to say a low end balanced amp is usually better than a high end SE amp, “under most conditions”? That’s not been my experience at all.

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