Review: Woo Audio WA7 Fireflies (3rd Gen)

Woo Audio WA7 Fireflies (3rd Gen) Headphone Amplifier

I appreciate it when audio companies continue to refine their products. While this certainly leads to some disappointment for purchasers of previous generations, the overall forward progression usually makes good on the promise of better sound for the same or incrementally more money. In the case of the Woo Audio WA7 Fireflies, the tube-based desktop amplifier is already on its 3rd iteration. And along with the default position of heightened sonics, the Woo family has updated a few hardware tech and specs to go along with their latest release.

It would be impossible to clearly evaluate the WA7 Fireflies without mentioning the industrial design. A significant departure from the rest of the company’s offerings, the WA7 shape pulls away from the “rectangle base with protruding tube glass” for a perfect cube outline. Even though the idea on paper is simple, it is extremely unique in a sea of similar-looking silhouettes for this category of high end headphone amplifier. Now mind you, the clear glass top that finishes the look is not permanently attached, so tube swapping is a breeze and pets and little hands are relatively protected from the heat. It’s a nice duality that isn’t solved as eloquently as one might think. The hefty glass piece also adds to the overall weight. At 8.5 lbs, the unit is quite heavy for the size, no doubt contributing to that number is the new inclusion of a linear power supply to the interior of the single box. The gen 2 option broke out the power supply into another cube, so those looking for more desktop space will be happy to see the entire package fits into a single 6” piece of real estate. Simply put, it is the most interesting-looking conversation starter that you will likely find on the market. That being said, outside of the deduction of overall boxes, not much has changed to the basic looks for the latest generation. What really shakes things up for comparison is the newly loaded internals. 

Woo Audio WA7 Fireflies (3rd Gen) Headphone Amplifier front

As with previous models, the internal amplification is a class A topology. But the tube stage is now updated to a more common 12AU7 option. Also adding access to the dual tubes is a pre out selector in the back, which allows for both 3.5mm single ended and a new 4.4mm balanced output. These options are also mirrored on the front panel for headphones. Woo sells a simple adapter that changes from the 5 pole TRRRS jack to the more common 4 pin XLR to make things easier. The output access on the back panel isn’t line level, but one could easily see the implementation used for desktop playback directly to a power amp, or to a pair of powered speakers set at max volume. Then volume control would simply revert back to the WA7, hopefully accessible from your sitting position as there isn’t a remote control option for the device. The knob itself turns with a fair amount of resistance, and is oversized in a flush-mounted fashion that works well for its intended use. The included USB-C terminated cable (the jack at the back of the WA7 is your usual USB Type B) worked amazingly well for connecting to a iPad pro, and provided no muss or fuss when connecting to the portable source. Of course, you can always bulk up the situation to a PC or Mac and the device is Roon compatible as well. Based around an ESS Sabre chipset, the digital decoding takes care of resolutions to 24-bit/384kHz PCM and 128DSD/5.6MHz – but no MQA at this juncture. 

There is also a pair of RCA inputs for funzies, but output is limited to the aforementioned 3.5mm and 4.4mm options. This RCA input did make for an easy A/B  to an external DAC, which drew tight comparisons. Switching back and forth from our Auralic VEGA, the best observation to glean was that sonic retrieval from the internal WA7 chipset was ripe with a classic sense of detail and refinement. A solid, crisp retrieval allowed for an easy, clean windowpane into the music. While the much more expensive VEGA turned in its smooth house sound as an audible difference, the SABRE on the Woo was able to showcase just how far things have come with digital decoding at both this pricepoint and relative size. There is just so much technology packed into this little powerhouse of a cube. 

As a preamp guiding a pair of Schiit Aegir power amplifiers, the Woo Audio WA7 Fireflies held its own against the matching Freya+ Schiit Pre ($949). The sound of WA7 leans into the tubes just a little, allowing for an easy integration for tube swapping while driving additional value to the entire idea. I offer this observation up as a small piece of contrast, as I found the high end WA33 amplifier from Woo Audio to lean into a slightly less colored and more solid stage-ish proclivity. This tube-friendliness also translated into the headphone output, allowing for good body in the mids while still maintaining tightness in the bass arena. There was also no treble falloff, and frequency response appeared robustly consistent with other amplifier options on hand – all of which brings us to an interesting buying choice of sorts. Consumers need to ask themselves, am I here for the tubes? If the answer is yes, then you may have found your huckleberry. You also can join the throngs of analog lovers in buying and collecting simple 12AU7 tubes and swapping them out for fun. As that group already knows, not all tubes produce the same sound, and changes in frequency response (as well as all sorts of other characteristics) can be augmented to suit individual preference – a good time and fun parlor trick all by itself.

Woo Audio WA7 Fireflies (3rd Gen) back panel

With the stock tubes, I found the WA7 to enhance the sound with just a touch of richness that I find myself preferring on most days. It’s still extremely clean, but perhaps with a smidge more of real life added to the mix (at least my perception of it). Listening to test tracks like the 2015 remaster of Fast Car by Tracy Chapman, it was plausible to hear just a slight enhancement to the vocal track in the most pleasurable way tubes can. It could be indistinguishable to some, but analog lovers know there is some allure to the way things play out in this sector of the hobby. Power was never an issue for any headphones on hand, which included both Dan Clark Audio Ether 2 open and Stealth closed cans. The less efficient 200 ohm Audeze LCD-4 took up a little more of the dial, but everything remained dynamic and punchy across the board for the WA7’s 1.5 watts of amplification power. No flab, no bloat, just clean playback with a tiny dash of romance. 

If you are looking for a desktop talk piece, or just want to look cool for your friends – the Woo Audio WA7 Fireflies 3rd Gen can help you that. If you like the warm glow of tubes on your desk and in your music then the WA7 is also there for you. The asking price of $1399 lands this piece on the high-end of headphone amplifiers for this physical size, but so much is packed into that space that enthusiasts for the brand and form factor can easily see where the value begins to take shape. Surprisingly, not everything in audio at this price looks as pleasing to the eye. Many products strike a very vanilla flavored effort when it comes to industrial design. The magic cube here looks and sounds great. The series has pulled out all the stops, and the 3rd generation now brings a handful of useful and practical options to the desktop to partner with all the latest sources (and headphones). Digital audio couldn’t be easier, and the whole package is a testament to the recent wave of high resolution streaming opportunities that were so long overdue. Things just work, and now they work in even higher quality from source to transducer. 

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