Reviews by Aetherhole


500+ Head-Fier
WA23 Luna - A Statement Piece
Pros: +Aesthetics
+Unit build quality
+Macro dynamics
+Large sound stage
+Timbral/Tonal quality
+Micro dynamics
+Customizability with tubes
Cons: -Higher Cost
-This amp and tubes gets hot
-Won’t be usable with IEMs or possibly even very sensitive headphones due to inherent noise
-Single-ended amp design
Statement Piece - A stunning statement piece can create drama or be a focal point. The point of it is to capture interest and stand out in your space.

The Woo Audio WA23 Luna is a statement piece, through and through. It draws attention. Its design elements stir up discussion. One can’t help but see the WA23 and immediately give pause. Its looks are unique; moreover, one of the most fascinating design elements is its duality. The color scheme of a solid black chassis and gold accent trim is exuberant yet refined. It’s both subtle and bold. It’s anything but a subtle piece of audio gear, but its design practically screams stealth. It’s so grandiose without being gaudy. It’s classy looking. It is one of the most tastefully designed pieces of gear ever to hit the market. For a piece of audio equipment, that’s well and good, but if it doesn’t function or perform well, then it’s all for naught. Thankfully, the WA23 doesn’t just create a stir with its aesthetics, it has the functional performance to back up its artistic design.

Typically, I lean heavily towards solid state amplifiers. I want dynamic range. I want punch. I want detail. All those things are easily found in solid state amplifiers without hardly any sacrifices. Moreover, all those things can be found without breaking the bank. Solid states that can drive difficult-to-drive transducers are in abundance and at affordable price points. The headphone amplifier world in previous years has been akin to questions like, “can it drive the Susvara?” In more recent years, it’s been refined to, “how well will it drive the Susvara?” Finding a solid state to be able to achieve that was a rarity, a crowning achievement, even. Forget about getting a tube amplifier that could drive such difficult headphones, back a few years ago. Nowadays, solid states that can drive the illustrious Susvara, among other difficult headphones, are a plenty. Tube amplifiers have made monstrous headway, and we now have some top-tier ones, like the Feliks Audio Envy, Cayin HA-300B mk2, Woo Audio WA33 SE and the EE, to name a few. And now also the WA23.


The WA23 Luna is certainly enough to drive the Susvara and to volumes louder than I am comfortable listening to, and it can do so beautifully, to boot. However, an important note: this will depend on how much signal voltage you are sending to the WA23. Gain staging is important here and if you’re DAC is feeding a standard 2v signal, it probably will not be enough to drive Susvara to a sufficient volume, or other hard-to-drive headphones. The Holo Audio May does just fine with the 5.8v XLR output. I have the WA23 set to low gain with the volume dial set between 12-2 o’clock, depending on the tracks. For extended listening periods, this is where I am most comfortable. I can push it to about 3 o’clock, but for longer sessions this is too much. For more leisurely listening, I might nudge it closer to 11 o’clock on the volume knob.

I’ve heard a lot of amplifiers in various capacities, but the headphone amplifier I’ve had the most extensive time with is the Ferrum Oor prior, so most impressions or thought comparisons are based off that.

I have tested pre-amping chains with the Oor and the WA23. Using the Oor as a pre-amp to the WA23, I did not particularly like what the Oor did to the sound. You really don’t gain much from this set up. With the WA23 as a pre-amp certainly adds some of the coloration and characteristics to the Oor, but ultimately, I did not find that the WA23 & Oor combination was a good fit. Most of my reasoning with this is because the WA23 outperforms the Oor in just about every aspect, which I’ll explain more in my impressions of the WA23. I could possibly see very specific use cases where it could be useful, but all in all, having the Oor in the chain did not improve the listening experience at all. The WA23 is just a better amplifier all together. I certainly will be playing with the WA23 as a pre-amp more when it’s finally my turn to have the Zähl HM1 in house, but a while off now.


So, how does the WA23 sound then? These words come immediately to mind— Beautiful, lush, authoritative, engaging, and effortless. Buckle up though, I’ve got a lot more to say.

When I first began listening, the first thought I had was, “wow, that is quite powerful.” My initial concern that the WA23 wouldn’t be sufficient enough for the Susvara was put to rest in the first 10 seconds of my first listening track. The first test track I used was Daft Punk’s “Give Life Back to Music.” The opening sequence of this song gives a good sense of how much impact it can have. As the song continued, the complexity of the jam-packed layering, really show the resolving capabilities of the amp. That was a fun introductory experience for this amp. I had every intention of switching tracks after the first track finished, but as the next song began to play, I remembered there were things that I wanted to hear there. Track after track played and before I knew it, I ended up listening to the entire Random Access Memories album. One of my favorite tracks on this album, however, is, “Giorgio by Moroder.” Starting at the 6:23 mark, there’s intricate details stacked in drums, synth, guitars, melodic line, and vinyl scratching. Attacks and decays of the various sound elements during this portion are a whole lot of fun. No matter how busy this sequence got, the sound was clean and effortless. The layering remained deep while well defined. The WA23 resolved all the details succinctly and, surprisingly, with more texture and body than I was used to. At the 7:45 mark there is a series of drum hits are blazingly fast, which can appear a bit muddied by all the added track layering, but the prominence here of the drum passage with accompanying thumps and cymbal splashes were never lost, once again, really displaying the effortlessness of the WA23. I will quickly add another favorite track of mine from the same album, “Motherboard.” Various instruments, like strings, flutes, and acoustic guitars, are interspersed with synth and drums that give so much body and life to the song that similarly impressed me.

Shifting gears away from Daft Punk, another track I listened to is Tool’s “Chocolate Chip Trip” from the Fear Inoculum album. This track, while less melodic than the tracks mentioned above, has several elements that flexes this amp’s strengths. At the beginning of this track there are wind chimes that are played in a bit of random sequences. They seem to hit and linger, ringing in a manner that exudes realism. I believe this perceived realism is due to the 2nd order harmonics from the tubes. The tiny bit of overtone series the tubes add, sweeten the sound of these chimes in a way I’ve not heard on any solid-state amp I’ve tried. Additionally, the various chimes come from different directions and distances in the sound stages. Another aspect of this song I really enjoy is the focus on Danny Carey and his drum kit. The splashes, slaps, hits, and kicks are distinctly tactile. There’s industrial sounds and synth that float back and forth through the left and right channels. The bouncing back and forth is persistent throughout, but amongst all the busy passages, it can get lost. Especially with the kick drums and crash cymbals, the panning and succinctness can often get lost. Not so on the WA23.

A track I’ve recently discovered that has made it into my regular testing/listening rotation is “Antecedent” by The Omnific. This progressive rock band is comprised of two bass guitarists and a drummer, a bass-head’s delight, for sure. There’s depth and heft inherent, but there’s also a ton of speed to the sound, as well. Also, the bass guitars have some effects pedals that are just really cool sounding. The note separation, especially in the lower registers, often blend together on lesser capable electronics or transducers. The combination of the rich timbre and transient agility of the WA23 pair marvelously with this track. The space between notes and drum attacks is palpable. Each strum and pluck of the metal bass guitar strings are almost felt as much as they are heard. No matter how quick, each onset is tangibly audible, and reverberate as such. The rest of the album, Escapades, is just as engaging and if “Antecedent” is right up your alley, listen to the rest of the album, too.

I’ve described a couple of parts of the sound reproduction of this amp already, gushing about the details and transient response, but one reoccurring standout aspect you might have picked up on certainly has to be the tonality, texture, and tactility of drums. The topic of tonality and tactility being at the forefront, lead to one of the most important aspects of my music enjoyment that I want to talk about next — Vocals.


I’m a classically trained vocalist. I sing semi-professionally in various forms, including mens chamber groups, large chorales, and church choirs, quartets, and solos. I say this only to illustrate that vocal representation is something I pay a lot of attention to. Classical, opera, choral, a capella music are types of music I thoroughly enjoy. Not limited to just those, though, vocals intrigue me in every genre, but I do have a soft spot for live music and live-recorded music. A go-to track that I use often comes from a vocal group called Voces8. From their album Eventide, the track,” The Seal Lullaby,” composed by Eric Whitacre, has the eight singers spread distinctly around the listener. Each of the singers' positions in the sound space are discernible, with each of the vocal parts coming from very specific directions. Each of their vocal timbres are well represented on the WA23. The harmonies and overtones that linger in the hall reverberate sublimely. The octet is also accompanied by a harp, which sounds heavenly and so, so sweet. It’s a beautiful song made even more beautiful by this amp. Other tracks on this album also have other instruments, like a saxophone in the track, “Quanta Qualia” that sounds elegantly smooth.

Keeping with the acapella theme, a mens chamber group that I love listening to is Chanticleer. Their rendition of Franz Biebl’s “Ave Maria” from their A Chanticleer Christmas album is one of my absolute favorites, partially because I’ve heard the group perform it live and because I’ve performed this song many times myself in the mens ensemble I sing with. It features four part mens harmony and also a separate mens trio, so seven separate parts. At the beginning of the song, the main group sings the chant in unison on the left half of the stage, but as they finish, on the right, you can hear a couple of quiet footsteps from dress shoes as the trio steps into place. These footsteps are pinpoint accurate where you can hear them on the right side at about the 2 o’clock position, but the reverberation of the steps of the hall just echoes as the trio begins to sing. It is quite marvelous. Each individual vocal part is noticeable as it is sung, but then just float away into the cavernous hall they recorded in. I’ve listened to this track probably a thousand times and the realism I get when listening on the WA23 is as close to the live performance experience as I’ve ever gotten, emotion and all.

I also must make mention of Geoff Castellucci’s cover of “Sound of Silence.” This bass vocalist has rich, deep vocals and a timbre that I really is impressive by itself. He layers his own harmonies with his own voice, so the timbre match is especially pleasing. However, notably, the sub-bass presence in this track is quite extreme. The depths will properly pressurize your headspace, testing the limits of the amplifier and transducer. The WA23 effectively took this track and said, “here, hold my beer…” keeping up with the demands and added texture and proper nuanced details across the board. However, just as impressive is the more intimate moments where I could more tangibly hear the press and lift of his hands on the piano keys at the beginning. Geoff’s plosive consonants, “t” and “s” and the softer “d” and “b” sounds also each had a touch more air and texture.

I will also quickly mention, I really enjoy listening to Billie Eilish on the WA23. Her intimate vocals really are markedly more engaging on this amp. And the macro dynamics of this amplifier really lend itself to this. I really like the track, “bury a friend.” Intimate vocals, authoritative bass, deep sub-bass, and plenty of opportunity for each element of the track to get lost in congestion, but the WA23 handles it aplomb.


What about Classical? One of my favorite albums lately has been “Tchaikovsky & Schulhoff: Orchestral Works” performed by the Pittsburg Symphony Orchestra & Manfred Honeck. Violins, violas, cellos, and double basses have real sonority. Yes, the strings sound wonderful, but the brass and horns really take the cake for me on this one. Trumpets can typically sound blaring to me, but with the WA23, there is trumpet prominence with no biting forwardness. The brass instruments all sound rich and pleasing, as do the woodwinds. The timpani and drums once again also have a good sense of tone, impact, and bounce to them. It is a really, really good listen.

While there are great instances to show off the treble response in the tracks that I have outlined already, one track that I want to mention specifically that brought a smile to my face was Janet Jackson’s “Together Again,“ from her album The Velvet Rope. The beginning 50 seconds feature a heavenly harp that glissandos a few times, panning across the sound stage. There are also some distant chimes that sound ethereal and angelic. Janet begins singing and the whole sequence just has this beautifully airy quality to it.

I have also listened to a good amount of hard rock and metal from various bands, like Metallica, Dream Theater, Korn, System of a Down, Avenged Sevenfold (their track “Nobody” was a real enjoyment on this amp), which can be intense and have a lot of bite and grit. For longer listening periods that normally would be fatiguing, I did not experience that with the WA23, in fact, I found myself more engaged as I was listening. A few things contribute to that— one: the drum kits, specifically the crash and hi-hats can be a bit much for extended periods of times but aren’t as edgy here. Two: guitars, both acoustic and electric, really have a more musical quality on this amp. Three: Drums have more tactility and punch on this amp and just simply sound better.


I truly cannot decide what aspect of the WA23‘s sound signature that I like more, it is all just so good. I have listened to hundreds of tracks and on countless albums, sometimes multiple times. Many times coming to the end of a track or album, and I think I’ve nailed down a favorite aspect, then I move onto another set of tracks or a different genre, I change my mind. I’ve written examples of elements of how it sounds and if you couldn’t tell, I am utterly enamored by it. Bass digs deep, its impactful, its textured, its full-bodied and lacking bloated, its realistic. Midrange range is rich, lush, and engaging, without being too thick and soupy. Treble is sparkly, immensely detailed, and free of harshness, all while retaining a very sweet quality to it. Let me be clear, though, I use words like lush and rich, but this amp is not dark. It does not sound muffled, rounded, or closed in at all. Transient response is superbly fast. Sound stage ranges from massive, when the song calls for it, to intimate when it needs to be. Holography is supreme with a remarkable level of depth and precision in layering within the sound stage.

I have a difficult time finding fault in the WA23 Luna. It’s not a perfect amplifier, as I mentioned earlier, but it doesn’t really do anything wrong outright. Other amplifiers outclass it in individual sound elements, but it’s not going to be huge margins there. The WA23 is just so well-rounded. I’m reaching when finding anything remotely negative to say about it. If I say, it runs hot or that it’s quite heavy, does that count? Well it does and it is, but that ought to be expected. Oh, I could mention as a negative, this could not be used with any of my IEMs. My 64Audio A12t and Thieaudio Monarch Mk III both had a pretty noisy, buzzing background plugged into it. I suppose, the aesthetics, while incredibly unique, will not be for everyone, either. There is no faraday cage to protect the tubes, if you are worried about that. Also, yes, this could be a deal-breaker to some, but the WA23 is a single-ended design and that may not appeal to everyone, though even with that, for convenience, there are XLR inputs and outputs that can be used.

There aren’t many pieces of equipment that have me giddy in anticipation to use, but the WA23 has me eager to press the understated golden power toggle. I simply get lost in the music with this amp; hours will go by while I listen. It’s been over six weeks since the WA23 arrived and not a day has gone by, whilst home, that I’ve not listened to this amp. It’s superbly nuanced yet grandiose in its dynamism, harkening back to what I stated at the beginning regarding the duality of this amp. I also stated that I lean heavily towards solid states, but the WA23 has me questioning all of that. Even with stock tubes, this thing is remarkable. Others might prefer a more clinical or neutral sounding amp, even within the tube realm, the Feliks Envy or Woo WA33 will likely fit the bill for those folks. Others might prefer an amp that will lean even more lush and romantic. Yes, there are other amps I’ve heard that have better individual characteristics, being more detailed or resolving, having a larger soundstage, having more lush, rich quality, or having better macro dynamics, but this amp stays right up there among the very best of each of them, all whilst staying uniquely well-rounded. It does it all, while being more musically engaging.

The Woo Audio WA23 Luna is a statement piece. And it is a work of art.

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@OhmsClaw thank you for reading the review! I love this community and the sharing of new music discoveries. Glad I could contribute back. Yeah, Geoff’s cover is bass intensive and on some IEMs, it is jaw dropping at the low frequency pressure you get from it!
Oh yeah man. Those Elrog 300B's, if they fit, are insane. I'm glad I demo'd them, thankful I don't have to pay to replace them.
@Aetherhole thats fair, if it ever has to go to a tech though maybe they can snap some pics. Woo seems really secretive about the internals


500+ Head-Fier
Simple Yet Effective Way To Change Your Sound / A Comparison Between the V6 Classic and the V6 Vivid
Pros: More inviting sound
Lush vocals
Slightly weightier bass
Richer more fuller mids
Relaxing and easier listening
Less analytical
Cons: Sound stage is smaller
Less precision within the sound stage
Not as articulate in the transients
weaker on the overall airiness
I was contacted by Burson Audio with an opportunity to sample the V6 Classic OpAmps. I jumped at the opportunity to give the Classics a try and compare them to the V6 Vivid OpAmps that come stock in the Burson Conductor 3X Reference I have been using.

Full disclosure: Burson Audio sent me these samples and in return I have only been asked to provide honest feedback regarding my findings.


I received the OpAmps a few days after first being approached and immediately installed them into the C3XR. For clarification, I’ve only been provided a single pair Classic OpAmps and the C3XR has place for two pair, for a total of four OpAmps. There are a pair of OpAmps for the L/P Stage and a pair of OpAmps for the I/V Stage on the circuit board. I have done listening with the pair of Classics in both stages, the L/P and the I/V. In my multiple listening sessions I swapped between the two stages to see what differences I was able to experience. I did find a little bit difference, which I will touch on in a little bit.


First, comparing the V6 Classics versus the standard V6 Vivids, I first tried the V6 Classics in the L/P stage and my initial reaction was there was a bit more sweetness to the sound. Acoustic guitar strums sound a little bit lively and tangible. There was a little bit more energy and coloration making it appear more palpable. Vocals also have a little bit more richness and body. Both male and female vocalists just had a little bit more lushness to their timbre. Sound stage on the Classics seem to have shrunk a bit though; the sound it produces is just a little bit more intimate. Instrument and detail separation within the sound stage appear to have less physical space between them. Vocals are more forward in presentation and they sound a little more in my head instead of out in front of me.


There appears to be less airiness to the sound. The trebles seem slightly more tapered and don’t quite have the same sparkle but there is still a beautiful richness that extends into the trebles. There may be slightly less energy in the treble range than on the Vivids, which make the Classics a little less revealing in nature. It probably is better described as a little bit less analytical in its sonic approach. Voices have a little bit less of a breathy quality to them, adding to that vocal lushness I had mentioned. Midrange overall sounds fuller and creates a little bit more of a warm sound. With both the reduction of the treble and the fuller bodied mids it provides a bit more of a relaxed, kick-back and listen approach.

Bass response seem just a touch weightier as well. The sound has just a bit more impact in the mid-bass region, but that impact doesn’t seem to extend to the lowest frequencies. There’s not less sub-bass compared to the Vivids, rather the mid-bass sounds slightly elevated. Kick drums have a stronger presence than on the Vivids.


While the Classics seem to have an “easier listening experience” feel to them, with warmth and richness, it comes at the expense of the speed in the sound. Articulation definitely is not as fast as the Vivids; however, this is not to the point of sounding smeared together. Transients throughout the frequency range seem just a little bit more rounded and smoother sounding. Attacks while they seem weightier don’t have as quick of an attack or onset and take ever so slightly longer to decay from.


Swapping the pair of Classic OpAmps in the I/V Stage and having Vivid OpAmps in the L/P Stage position, I would say mostly things are more similar than different to my findings stated above, however there were a couple things that I did note as sounding different. The first thing I had written in my notes was a little bit more weight and presence in the bass. The sound stage size felt about the same size in width and depth, but I did note that the sound seems a touch more ambiguous. What that means, delineation within the sound stage seemed a little bit blurrier. Main vocals sounded a little broader and less centralized, as if it was filling a little bit more of my headspace. Detail retrieval and articulation seemed about the same with the Classics in the I/V Stage versus the L/P Stage.


While I’ve taken time to pinpoint the differences that I experienced between the stock Vivid OpAmps from the C3XR and the Classic OpAmps that Burson graciously sent over to me, I will be candid and say that the differences are not as monumental as, say, changing amplifiers entirely. These OpAmps provide subtle changes that don’t drastically alter the original characteristic of the amps they are installed in. That being said, as I’ve aged my listening experience and what I look for in my sound characteristics has shifted. I used to truly value lushness and that relaxed, laid-back listening experience, which would have put the V6 Classic OpAmps right in my wheelhouse. Nowadays it seems that sound stage, precision, articulation, neutrality outweigh my earlier preferences in sound. That said, there’s no real wrong way to listen and I think Burson in their expertise knew that when making and offering both the Vivid OpAmps and the Classic OpAmps. Each have their strengths and their weaknesses, but having flexibility to OpAmp roll make trying to figure out just what suits your listening preference an easy and relatively inexpensive option. So while, I will likely stick to the Vivids for my listen experience, I certainly will whole-heartedly recommend you try the Classic OpAmps to see what it can do for your listening experience.

For referential purposes the equipment that I used was my iMac with Tidal fed via USB to the Burson Conductory 3X Reference. For headphones, I used both the Hifiman Arya and Hifiman Susvara. And here’s a list the songs that I listened to throughout my listening session:

Inquisition Symphony - One
Sound in Spirit - Como Pod’ a groriosa, Night Spirit Song
Hans Zimmer
Batman Begins - Molossus
Dune - Dream Of Arrakis, Herald of the Change
Inception - Dreams Are Collapsing, Time
Interstellar – Mountains, No Time for Caution
10,000 Days – Jambi, 10,000 Days, The Pot
Michael Buble
Call Me Irresponsible - The Best Is Yet to Come, It Had Better Be Tonight, Everything
Ludwig Goransson
Tenet – Priya, 747, Sator, Trucks In Place, Inversion, Algorithm
Imogen Heap
Speak For Yourself - Hide and Seek, Have You Got It in You?
Frou Frou
Details - Let Go, Maddening Shroud, Shh, The Dumbing Down of Love
Will Smith
Big Willie Style - Gettin’ Jiggy Wit It, Just The Two of Us
Mormon Tabernacle Choir
Sound of Glory - Battle Hymn of the Republic
Corner of Broadway and Main Street Vol 1 & 2 - Disney Love Medley, Bring Him Home, You Will Be Found, Remember Me, Prince of Egypt Medley
Symphony & Metallica - Enter Sandman, One, No Leaf Clover, Master of Puppets
Billie Eilish
When We All Fall Asleep, Where Do We Go? - Bad Guy, Bury a Friend, ilomilo
Nora Jones
Come Away With Me - Come Away With Me, Nightingale , Don’t Know Why, The Nearness of You
Jack Johnson
In Between Dreams - Better Together, Sitting, Waiting, Wishing, Crying Shame
The Love Club - Royals
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Thanks for your compliment! Regarding the Classics in the I/V stage, I definitely didn't prefer them there. As noted in my review, I found the sound to be a little bit more ambiguous and a little bit less localized. It didn't add sound stage as that might make one believe, but it just felt less sound stage accurate. Vocals also inherited the same characteristic, too. To my ears though, the bass felt just a touch weightier though. The difference wasn't stark though. I think if anything, putting them in the L/P stage is definitely the way to go, but! Nice thing is, you can try it and see without too much effort!
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Totally understand. I actually prefer mines in I/V stage as I like super lush and musical tonality to the Susvaras. The LP was awesome but the base impact and dynamic I felt came a bit more alive while on the I/V stage for me. As for the full vivids, it's super clear but can get to glary for me with the ess dac. I usually listen to music as I work for about 5-6 hours so it gets quite fatiguing.
One of the greatest things about the Burson products is the ability to cater it to the user. And yep, I agree-- bass was a bit more prominent in the I/V stage for me too. For my personal taste, the clarity gained with the full Vivids pairs well with the Susvara. I think, the Aryas (v3) being a bit more brighter than the Susvara, the Classics would probably be more agreeable to make the treble less energetic. Still, I don't find the Arya Stealth to be too bright 90-95% of the time; on select songs or albums it can have a bit of glare.
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