Review: Woo Audio WA22 headphone amplifier


I’m willing to put up with a lot of ugly in my audio – the various Nextel-painted Tannoy DMTs that have graced my living room attest to this – but my personal hierarchy tends to go something like:

  • Does it sound great? Win.
  • Does it feel good to use? Do the switches “thunk” solidly? Is it ergonomically pleasing and not annoying to use? Win.
  • Do I like how it looks? Extra gravy on a bowl full of win.

Let’s face it, if I’m shelling out mad money for my audio gear, I want it to look good and feel good, as well as have it sound awesome. For almost as long as I’ve been following hi-fi, Woo Audio‘s gear has topped my mental list of the most attractive products out there. For the most part, Woo’s products are rather deceptive in their simplicity – it’s just milled aluminum and tubes, right? What’s the attraction? But getting the fully-balanced WA22 headphone amp in-house really shored up my gear lust.


Thanks to the good graces of Woo Audio’s Mike Liang, I received for review a black WA22 ($1995) with the optional upgrade tubes, a GE 6080, a Westinghouse 6SN7 and Sophia Princess 274B tubes. The Sophia rectifier, which is available from Woo for an additional charge of $160, is a serious work of art, the kind of thing that provoked visitors to stop and study the rack and say things like, “What IS that?” and not in that, “Dear god, what is that thing?” kind of way, either. The rest of the amp is equally good-looking, if in a more understated way; the milled brushed-aluminum case work is beautifully constructed, with tight seams and an impressive solidity.

Not only is it dead-sexy, the WA22 is also enticing to touch and a pleasure to use. The big, chunky volume and gain adjustment knobs are milled aluminum; the volume knob turns smoothly, with satisfying resistance, and the combined power/gain selection knob clunks authoritatively into place. Between these two knobs, the front panel also features ready access to two sockets for balanced three-pin left- and right-channel headphone outputs, a four-pin balanced output, and one single-ended headphone output.

The WA22 is a straight-up headphone amp: no double duty with your loudspeakers, here. The back-panel featured one single-ended RCA input, one balanced XLR input, and a switch to toggle between the two. I found all the inputs and outputs to be of good quality, with nary a loose cable to be found. Teflon tube sockets, also milled in-house, grip the tubes tightly. Between the build quality and the serviceability, you will not mistake it for some disposable toy.


I did the majority of my listening to the WA22 with two different set-ups. The first was my home-brew Linux server paired with the MHDT Labs Havana DAC (the same system referenced in my recent MrSpeakers Alpha Prime review). The second was using the Oppo HA-1 headphone amplifier as a digital source, which had the benefit of access to higher resolution files, as well as a rather different sound signature. The input cables in both cases were White Zombie silver balanced XLR cables.

Given the opportunity to put the amp through its paces with every pair of headphones that came to hand, I took full advantage, trying out a broad range of headphones at every price point. The full list: Grado SR80s, AKG 702s, MrSpeakers Alpha Dogs and Alpha Primes, Oppo PM-1s, Sennheiser HD800s, and Audeze LCD-3s. Whew!

Other associated equipment: my comfy couch and my knitting needles. Because I’m just that cool.


In pairing the WA22 with various sources and other equipment in the chain, I found that it lets the signature of the other components through, but does impart some of its own touches to the mix. This calls for selecting to taste. Paired with the tube-buffered Havana DAC, the sound is romantic and a bit thick and warm: a classic tube sound. By contrast, I found the combination of the Oppo’s overall leaner sound with the WA22 to be a much less laid-back match: the sound remains nimble, with just a suggestion of some tempering of the harsher edges. This held true for the quality of the tracks, too; lower quality tracks sound good, but are not made artificially smooth through sins of omission. It seems like saying good quality tracks sound good and better recorded tracks sound exponentially better should be the most obvious “well of COURSE they do” thing in the world, but that’s not always the case; I’ve occasionally found that amps that make everything sound good also fail to allow the truly stellar tracks shine. That is definitely not the case here.

As I mentioned above, I had a true embarrassment of riches in terms of headphones available for testing. At first, I did most of my listening with the MrSpeakers Alpha Dogs and Alpha Dog Primes, as I was completing my review of the Primes at the time. The versatility of the Primes served me well in this case; finding the sound signature a bit dark with the previous Prime tuning, I moved the tuning dots around in order to find a more neutral tuning that suited the WA22 better. This was especially necessary with the Havana in the chain, but I found I still preferred this more neutral tuning when using the HA-1 as a source. The Primes yielded wonderful results with First Aid Kit’s Lion’s Roar, particularly on the bonus track “Wolf.” The driving percussion on this track was incredibly solid, with a real sense of mass and weight behind it. This amp is not light in its loafers.


It’s also incredibly quiet. I was mildly obsessed with the Quiles & Cloud album Seminole Star during the entirety of my review period for the Primes, and one of the things that really struck me about listening to it through the WA22 was just how inky black the background was on some of the more spare tracks, with not a hint of tube noise or hum to mar the quiet moments. This held true no matter what headphones I used; I kept picturing the band performing in front of a black velvet backdrop, thus proving that my imagination can be astonishingly, banally literal at times.

Of all the headphones in my available arsenal, I found the best synergy with my Sennheiser HD800s with Double Helix custom balanced cables. The HD800s are some of the best headphones I’ve encountered in terms of soundstaging and detail retrieval: they are amazingly airy and engaging. They can also be a bit brutal, depending on the amplification; with some amps, I find the treble a little spiky, and long listening sessions can be fatiguing. The HD800s and the WA22, in contrast, go together like chocolate and peanut butter, milk and cookies, peanut butter and jelly… Mmmm, I’m hungry now.


Right! Anyway. This combo really showed the strengths of the WA22. Any fatigue I had experienced with the HD800s in other situations completely disappeared; instead, I found myself easily losing hours to the music. Zoe Keating‘s Into the Trees was tear-inducingly transportive, with all the texture of the cello coming through exceptionally well, including the body resonance of the instrument. Yo-Yo Ma’s Cello Suites similarly showcase that instrument with magnificent realism, in this case also offering an outstanding sense of the recording space. While the treble “played well” with the HD800s, I didn’t get the feeling this was due to any kind of artificial roll-off or veiling; instead, the treble simply sounded more real and natural.

Reluctantly switching gears away from the cello-riffic, I took Tori Amos’s Unrepentant Geraldines for a spin, with the intention of trying something a little more poppy. The album really showcased how nimble the WA22 can be. “Trouble’s Lament” is a classic Tori track that starts out a bit ominous (“Trouble needs a home, girls…”) and then slowly turns into something a little more rollicking, with double-tracked harmonies and a little growl in the chorus. At times there’s a lot going on, with all the multiple layers of voices and instrumentation, and the WA22 handled this with confidence and an energetic snap. This was similarly in evidence when I took the Oppo PM-1s for a spin.

I found this energy somewhat absent when I tried pairing the WA22 with another favorite set of headphones, the Audeze LCD-3s. While the tone was truly beautiful upon revising Zoe Keating, and the sound very rich and full, I couldn’t shake the feeling that there just wasn’t quite enough power to drive these headphones. The darkness I’d experienced with the earlier tuning of the Primes was in full effect, as was a certain sense of sluggishness. All the agility I’d found so entrancing with the Senns had vanished. Listening to Bill Evans and Jim Hall’s “My Funny Valentine,” I appreciated the bell-like tone of Hall’s guitar, but I don’t think I’ve ever heard the track sound this laid-back. I’m not sure I consider this a good thing. I know from experience that the LCD-3s bring excellent detail retrieval to the game in other situations, so I reluctantly concluded that this was not a good pairing for my kind of listening. For others who prefer a more meaty, rounded, and romantic sound, it may be a-ok.

There’s an understanding, I think, that pricier headphones deserve high-quality amplification. This makes sense: if you’re paying a grand or two for a pair of headphones, you want to make sure you’re hearing what they’re fully capable of. What’s sometimes overlooked, though, is what high-quality amplification can do for less expensive headphones. I was reminded of this when I decided to snag my husband’s pair of workhorse AKG 702s off his desk and give them a try with this amp, just for fun. Now, he’s always maintained that these punch out of their weight class, and I’ve always thought they were indeed quite good (especially given that they can usual be found for $250 or so on Amazon), but I still wasn’t quite prepared for how eagerly they would respond to truly sympatico amplification. Hooked up to the WA22, these things practically did a song and dance number, and provoked comparisons to the HD800s – not quite the same soundstage or clarity, but the WA22 brought them remarkably close to the same ballpark in terms of tone and liveliness.

Hooking up my old Grado SR80s brought a smile to my face, as well; The Goat Rodeo Sessions with Yo-Yo Ma, Stuart Duncan, Edgar Meyer, and Chris Thile had me kicking up my heels a little, especially the bluesy swing of “Quarter Chicken Dark.” While they still have their shortcomings in terms of detail, it was great to re-learn how musical they are — and how great they are with strings and vocals.

Listening to my Grados on this amp was almost like the same kick you get from revisiting an old favorite album – I remembered why I’d fallen in love with them in the first place.


It’s possible to saw on for ages arguing about the “best” way to approach an upgrade path for headphone listening. Do you go with your dream headphones first, and then follow suit with your amplification, or the other way around? I don’t have a vested interest in one path or the other, but the WA22’s performance, even with my lower-priced headphones, presents a strong argument to be made for leading with a high-quality, versatile headphone amp. That will let you get the most out of what you have — right now! — and will pave the way for further upgrades down the line.

I would argue that the more beautiful something is and the more pleasant to use, the more it will BE used. The WA22 fits the bill on both counts, and it’s built like something you could hand down to your offspring. Depending on the direction you plan on taking your system – particularly if that direction includes Sennheiser HD800s or similar – the WA22 could just be the perfect component to take you through many years of listening.


About the Author

kirstenKirsten Brodbeck-Kenney met her first halfway-decent hifi setup in 2007 and has been bogarting the sweet spot ever since. She lives on the Oregon coast with her husband Malachi, a pit bull named Hank, some ridiculously huge speakers that she insists are “not really that big, really,” and an ever-growing collection of vinyl. In Real Life(tm), she is director of the local public library and answers to “Hey, Library Lady!”

You can find her show reports scattered across this site and our companion site, The Audio Traveler


  1. Excellent review! Very much enjoyed reading it, funny and quite informative too.

    Though I don’t own Woo Audio amp’s, I have been a fan of them for a long while, alongside Schiit Audio, CEntrance and iFi Audio.
    I thoroughly enjoy my all-in-one iFi Audio Retro Stereo 50 vacuum tube DAC/amp/headphone amp/phono/bluetooth (fully single-ended) and it made my AKG K 712 headphones SING!
    I also use three iFi Audio USB accessories: Gemini dual-headed USB cable, iUSBPower supply, and iPurifier 😉
    Just waiting on my Audeze EL8 closed back headphone and SubPac S2 to complete this setup.

    But even so this WA22 sounds amazing, though a bit more power could have been great for certain planar headphones.

    One thing that I think is missing in the review is if you encountered any differences between single-ended and balanced, and which headphones did you use in SE or balanced mode (AKG K702 & Grado SE80 are SE ofc, unless I’m wrong…).

    Thanks again Kirsten! d^_^b

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