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Woo Audio WA22


Pros: Warm smooth sound. Deep Bass. Sweet Vocals, Low Hiss

Cons: Lacks the Impact, Initial Tubes are not that great


The WA22 is my third Desktop Amp and second tube amp. I got it through AV One, a local retailer here, after 2 rounds of testing and I was impressed enough to purchase it.


Built like a tank and weighed more then 10KG, the WA22 is one of the nicest looking amp that gives a the buyer confidence. The volume knob has stops built in. Personally I prefer a smooth knob with good tension but the one on the WA22 is really smooth and the volume increase usually hits the amount I need to so no complaints. The only amp I that felt better using is the studio six by ALO but I guess its really subjective to each individual..



The WA22 is a very smooth amp with good warmness. Through my vocal songs by Suara and Susan Wong, this warmness makes the vocal all the more realistic and pleasing to hear. Especially in the phases where the vocal dominates most of the sound, it gives a feeling of a upfront small little hall that the singer is there to express her song. Theres also a slightly longer decay that adds on to the smoothness that makes the WA22 a blast to listen for vocals.



Listening to more pop music however lacks the absolute impact in those bass and the shimmer in the high. Everything feels tamed and yet extended. It feels some excitement is actually lost in the music compared to my hybrid tube amp ALO Continental Dual Mono. This is however mitigated a little with the usage of Sylvania 6SN7GT which I replaced over the default tube.  For the lack of impact of impact, the WA22 bring about quite some depth in the lows and plenty of clarity. This can be felt in the various sound tracks from Final Fantasy Distant World series. Separation is also great, allowing each instrument to be identified. However their exact positioning is definitely not the absolute best: the studio six which I had a chance to also try out is better at it, though it cost twice the price!



With all its power, its a great amp to drive the planars and likes of K701. My HE500 was really revived with the energy the WA22 gives it. The K701 with the WA22 has plenty of clarity and a nice warm sound stage. It doesnt feel as wide as the WA5 that I tried out, but it feels more realistic like a good sized room. It also drives IEMS quite well. My Lyra had no hiss from the WA22 even when the pot is turned more then 50%.



If one major issue I have, is the original tubes that comes with it is rather bad. Just changing it really improves the entire amp by a good margin. My current favourite for vocals is the RCA 6SN7 while for general listening, the Sylvania is a great generalist for most types of song. My rectifier is a RCA 5U4G, definitely going to try a Metal base Mullard 5ar4 one day.


In conclusion, the WA22 is a great amp especially after some basic tube rolling. It may not be the best if you want the best seperation or sound stage, but if vocals are the main course of your music, then this amp is extremely enjoyable and worth the space and cost.


Pros: Excellent tonality; cohesive, organic sound; wonderful pride of ownership (aesthetics and build)

Cons: Slightly less leading-edge transient detail than some; slightly less treble extension than some.

[This is copied from the Music City Meet #3 Pics and Impressions thread, post here.] 


A Few Impressions of the Woo Audio WA22



Intro: Mike at Woo Audio was kind enough to lend me the use of his WA22 for the Music City Meet #3 and a few weeks before. As it happened, and to my dismay, I did not get to spend the amount of time with the WA22 that I would have liked to have had-- the non-HF world was pretty crazy for me there for a while prior to the meet. I finally got a chance to sit down and spend essentially an entire day listening to the WA22 and taking notes, so I hope there is still some value in my notes, even if they weren't the result of as many listening sessions as they probably should have been. Many, many thanks to Mike and the Woo Crew for their generosity and support!! From the feedback I got at the meet and afterwards, I'd say that the three Woo amps in attendance (WA7 with WA7tp, WA5, and of course the WA22, all with upgraded tube sets) were overwhelming successes with the guys at the meet-- although the WA5 definitely upstaged its smaller (and less expensive) siblings, naturally befitting its reputation as a truly world-class amplifier. 


I kept trying to make time to sit down and type up a more formal review, but other stuff kept coming up and forcing me to postpone, so I'm just going to go with the experiential model for reviewing and provide you with my actual listening notes (with some editing for clarity, spelling, etc). With that in mind, please excuse the rather haphazard 'organization' to the notes below-- I would often listen for something, compare, and then go to something completely different to determine how another parameter sounded, or how the same parameter sounded with very different music. 


Note: I am not certain precisely what tubes were sent with the device (Mike might be able to chime in with more info), but there was one Sophia tube, two Westinghouse tubes, and two of something else I managed to miss jotting down... 


Personal Preferences: I do want to take a moment to point out my own listening preferences, as I find that to be a crucial (and often overlooked) datum in a review that allows the reader a little better context for determining how one person's impressions would line up with their own. I have found that I tend to value texture, tonality, and transient detail very highly when listening, while I give very little weight to soundstaging (I often cannot place instruments particularly well, probably due to califlower ear from sports). I should also mention that tend to prefer solid state over tubed gear, as a good bit of the (admittedly narrow) experience I've had with tube gear in the past strikes me as a bit too lush at the expense of accuracy, although I do not have the technical knowledge necessary for a preference beyond the sound itself. 


When I listen for enjoyment at home on the HE-6, I do so from the Pass Labs F5 speaker amp clone (using the Audio-gd Master 8 as preamp). When I listen to basically anything else, I use either the HP out on the M8 (balanced when possible, SE when necessary) or the SE HP out on the Hilo. Although, to be frank, I didn't even have my setup functional for about a month prior to listening due to various digital gremlins and the aforementioned other time constraints. 


Also, there will be some test tracks used that many of you probably will not be familiar with, and probably would not care for much. Understand that although it might seem utterly random which track follows which, there was a logic in the moment of tracking down some quality I was attempting to better understand. And the tracks I used were generally ones I'm very familiar with-- while Kind of Blue would have certainly been a better reference for many Head-Fiers, it's not an album I've listened to enough to be able to use as a critical listening tool-- yet, anyway. A few tracks were just oddball picks in the moment (like the Daughters track) based on something I was trying to better delineate. 


Frequency Preferences: I believe Tyll would describe my tastes as tending towards the slightly bright side, but I don't hear the cans I particularly like (HE-6, T1, T5p, LCD-XC, ASG-2, etc) as being bright, but as being more accurate than headphones with (to my ears) a more veiled or 'laid back' approach. I find a lack of treble extension and articulation particularly distracting, and it often decides which headphones I keep and which ones I don't. The midrange is crucial for nearly every type of music, of course, but I particularly gravitate towards gear that nails the tone and texture of guitars (electric and acoustic), as most of the music I typically listen to is guitar-driven. If something can't do guitars well or sounds wrong to me (like the HD800), I generally find I can't move past it. With bass, I prefer (again) texture and tone over emphasis for the sake of emphasis, and dislike it when an overemphasized bass affects the midrange (as it generally flabs-up the guitar sound that I love). I do, however, appreciate a punchy bass when called for. I occasionally listen to bass-heavy music, but not often. 

Setup: Dell Venue 11 Pro running JRMC 20 > Lynx Hilo > Audio-gd Master 8 > Woo Audio WA22. All listening was done on Hi output setting.

Listening Notes
Started off listening to a few tracks on the Master 8 with the Alpha Dogs (stock balanced cable) to establish a baseline for comparison. 
Tool, "The Pot," 10,000 Days: listened to the M8 into Alpha Dogs in the background while messing around on the internet for a few minutes to allow my ears to acclimate to the sound. I made an attempt to avoid analyzing the sound during this time and just let it play. 
Steely Dan, "Brown Cow," Aja
-M8 to WA22 switch: Immediate switch impression: a bit more organic, more cohesive, a touch more smooth/rounded sounding, possibly more immediately enjoyable? 
"Deacon Blues"
-WA22: The light guitar strumming sounds really good. Vocals a touch recessed? Might just be the track, as the vocals aren't particularly forward in the mix. 
-Switch to M8: a touch cleaner? Less organically cohesive, slightly. Less midbass emphasis? Strummed guitars sound good, but not as good. Don't know that it's any more detailed or textured than the WA22 in direct comparison. Don't know that I have a strong preference between the two amps with Steely Dan. 
Umphrey's McGee, "Anchor Drops," Anchor Drops
-Starting on M8. Sounds hollowed-out, like it's being played in a box, sensation disappates a good bit after vocals start. Good delineation of different instruments and things going on. (Alpha Dogs, while excellent headphones in general, have a bit of an artificial sound in the treble that is more apparent on some tracks than others). 
-Switch to WA22. Touch warmer, more cohesive, vocals sound a bit better. Various instruments don't sound so dramatically separated, which actually sounds more natural. This music suits the WA22 pretty well. Song moved over to "In the Kitchen" and I just let it play for a minute. Surprisingly, I preferred the WA22 here. 
Masada String Trio, "Tufiel," Azazel: Book of Angels Vol 2:
-Starting w/ WA22: Everything sounds very pleasingly connected and cohesive, but does sound just a touch smoothed-over, like a touch of the texture of the strings isn't there. Very, very pleasing though. 
-Switch to M8: Touch more sterile sound, but slightly better texture to strings. Definitely a touch less organic sounding, but doesn't sound as almost aggressively disconnected (in terms of instruments relationships to one another) as Umphrey's McGee did with the M8. Kind of expected this to be better on the WA22 than the M8, but it's actually pretty close. 
-Switch to WA22: transients slightly less well-defined, but that organic sound is very nice. Bassline seems more three-dimensional. Just a very slight bit less string texture. 
While this one would ultimately come down to personal preference, as it's quite close, I somewhat surprisingly preferred the M8 here. 
Clutch, "The Mob Goes Wild," Blast Tyrant
-Start w/ WA22: immediately very engaging. Guitar tone and texture sounds good! Percussion sounds very 3D. 
-Switch to M8: very close. Drums not as 3D sounding. Guitar tone and texture is very good, although it might actually be a bit better on WA22. Sounds maybe a hair cleaner? Guitar distortion sounds maybe a touch less tonally accurate than WA22? 
Again, very close, and it could come down to the preference on a given day. But I give the WA22 the slight edge. 
Note: Switching to Beyerdynamic T5p (modded w/ dual mini-XLR inputs, clear gel pads, Q-Audio cable). Note: I feel that the T5p has significantly better treble articulation than the Alpha Dogs, but does not have nearly the bass presence of the ADs. 
Jerry Cantrell, "Cut You In," Boggy Depot
-Start w/ M8, sound is immediately different after switching from such a different sounding headphone. After some acclimation, guitar texture sounds absolutely excellent. Cymbals are a bit splashy, don't have great tone, might be the recording. Listened to whole track here to begin with, switching over only after song is completed. Bassline sounds somewhat buried. 
-Switch to WA22 (restarted song): Warmer, more bass impact than M8. Cymbal crashes still sound splashy and indistinct, and still have poor tone, so must be the recording. Guitar tone is maybe a touch more accurate, but slightly less textured. 
Too close to call here. 
The Mars Volta, "The Widow," Francis the Mute
-Starting with the WA22: heard some kind of noise within first 8 seconds (sounds kind of like the sound of an ocean through a cardboard box) that I haven't noticed before (haven't listened to this track in quite some time). Sounds good. Vocals are a hair recessed. Something about track sounds slightly artificial, can't put my finger on it. 
-Switch to M8: vocals are brought forward again, artificial sound isn't there anymore. Sounds better on the M8 than the WA22. Sound is a touch more delicate, maybe? 
The M8 edges ahead here. 
Daughters, "Recorded Inside a Pyramid," Hell Songs
-Started off w/ M8: Guitar tone and texture is very good. Differentiation of instruments is very good. Cymbals are a bit falsely crystalline sounding and decay much too quickly, but I'm pretty sure that's the recording. Drums sound a hair muffled or overdamped, again probably the recording. 
-Switch to WA22: more organic and cohesive, but not quite as sharp, transients not as well defined. I'd imagine which is better here comes down to individual preference. Cymbals still sound like s__t, definitely the recording. Drums are still not great, but sound a bit better here than on M8. Maybe a touch less extended in treble than M8? Guitar tone is really good, guitar texture a touch smoothed-over. 
Radiohead, "Jigsaw Falling Into Place," In Rainbows
-Starting w/ WA22: wow, this sounds really, really good. Organic, warm, cohesive, just really good. Not fully extended in the treble. Vocals are still just a hair recessed. 
-Switch to M8: immediately a touch more clear, sounds more open on top end. Vocals still a touch recessed, sound vertically higher in soundstage slightly? Got kind of lost in the music and my thoughts for a minute. Again, I think preference here will come back to what one prefers. I think I actually prefer the M8 just slightly. 
Note: Had to power cycle the Hilo, so took a quick break. Decided to do a little reading while listening to headphones to fully acclimate to the sound. Listened to a bit of Tool's Lateralus, and a lot of Masada's Live in Sevilla 2000, all while still listening to the T5p on the M8. 
Protest the Hero, "C'est La Vie," Scurrilous
-Starting w/ WA22, definite midbass bump. Instrument separation is very good. Bass gets a touch woolly and a bit buried in the mix as a result. Guitars sound very good, not best texture I've ever heard, but very good texture. Cymbals are somewhat indistinct and harder to pull from the mix, but sound tonally decent as long as they aren't crashing, at which point they get a bit splashy. 
-Switch to M8: Immediately more clear, no midbass emphasis. Texture is better here, and tonality may be a touch better too. Bass is still buried, probably the fault of the T5p. Cymbals are significantly easier to distinguish, and actually have a little tone during crashes (although still not great). Overall instrument separation and balance is better with M8. In general, while I like the sound of both of them, M8 is better here. (This is a track with which I'm exceedingly familiar across a number of different setups). 
Cryptopsy, "Carrionshine," Once Was Not
-Starting w/ M8: Drums sound a touch cardboard. Cymbals sound good though. Guitar texture is great. Double bass sounds good. Sound gets a bit congested around 1:20 with a lot going on. 
-Switch to WA22: Guitar slightly masked, but overall sound is very good. Sounds just a touch veiled in comparison to the M8, but that isn't necessarily a bad thing here. Again, everything is more of a cohesive, organic whole here. 
Dillinger Escape Plan, "Farewell, Mona Lisa," from Option Paralysis
-Starting w/ WA22: Midbass emphasis is back here, tends to thicken up sound a bit in a way that I don't think does well with the music here. Bass drum kicks when music gets more sparse around 1:50 sound slightly off somehow, kind of cardboard and echo-y. 
-Switch to M8: expected it to be a lot clearer with this track based on my impressions w/ the WA22, but it's just a touch clearer than the WA22. Vocals are definitely better though. Lack of midbass hump is helping guitars come through more clearly. If you could have a touch of the organic cohesiveness of the WA22 with the articulation and clarity of the M8, you would have a world-beater. Double bass drums still don't sound great (again, attributing this to the T5p, as bass is not its strong suit). 
Note: Switching to Beyerdynamic T1 (single-ended, no mods): also listened to some DEP after the switch, and it sounded much better with the T1 than the T5p. 
Clint Mansell, "Winter," Requiem for a Dream OST
-Starting w/ M8: Sounds damn near perfect. Keyboard in 'Full Tense' sounds really good. Bassline and keyboards sound great!
-Switching to WA22: Also sounds great... Not sure which I like better here. Started back from the beginning, although I didn't finish "Winter" on M8. 'Full Tense' sounds maybe a touch less crystalline than M8, but still sounds very good. Man, I don't know which one I like better here. 
-Switch back to M8: during 'Fear,' definitely clearer, more accurate, sounds maybe a bit more tonally correct. Okay, I think I prefer the M8 here. But if I didn't have the M8 on hand, I'd absolutely love the WA22, and still think it sounds great.  
Juana Molina, "Quien?" Segundo
-Starting w/ M8: Her voice sounds basically perfect, guitars sound really good. Percussive sounds are right in your ears, as JM often does. 
-Switching to WA22: sounds a bit fuller, more tonally accurate? Guitars have a bit less transient clarity. Vocals sound great, more about nailing the tone and emotion, doesn't get all the texture, but gets the gist quite well. Percussion is less distracting and annoying here, still in your ears, but rounded into a more pleasing form. 
-Switch to M8: Transients are a bit better, but percussion in ears goes back to being more annoying. Sounds really good, but I think I prefer the WA22 here. 
Marcus Miller, "Bruce Lee," Silver Rain
-Starting w/ M8: sounds great! Bass is in front, while percussion and other sounds are more to the sides. Background voices that follow the musical lines are something I hadn't noticed before. Not wanting to switch to other amp, just because I'm enjoying the groove!
-Switch to WA22: bit warmer. Non-bass instruments don't sound so jarringly separated from the bass guitar as on M8. More emotionally enjoyable than M8, if less technically able (transients, etc). Horn sounds really good though! Leading edge of notes is well defined, sounds solid state with horn on leading transients, but has that tonal accuracy and warmth on the actual note itself. Very, very nicely done on the horns. Still feels a touch closed-in due to the less extended treble, but only in comparison. Too close to call, love them both here. 
Juana Molina, "Rio Seco," Son
-Starting w/ WA22. Sounds absolutely great. Guitars sound just a touch closed-in still due to lack of extension. Other than that, guitar sounds really, really good. If this amp had a touch more solid-state-esque articulation (transient detail, texture detail, treble extension), it would be a force to be reckoned with. 
-Switch to M8: transients better defined, more clear. Percussion does not sound quite as good though. (Restarted song b/c it ended). Guitars still sound a touch closed-in, so not the fault of the amp. Voice definitely has more texture, but does not have same organic smoothness. Something about this sounds a little less spiritually accurate and alive than WA22, although only in directly comparison. Transient sharpness in vocals is a definite improvement though. Music sounds a touch more confused than with WA22. 




So, did the WA22 wipe the floor with the less expensive Master 8? No, and neither did the Master 8 show up its tubed counterpart. Had I been a WA22 owner reviewing and comparing the Master 8, I think I would come away wishing the WA22 had a couple characteristic strengths of the Master 8, but I would have not felt compelled to make the change. Similarly, there are a few qualities (that seemed especially strong on several tracks) of the WA22 that I wish my Master 8 had. Ultimately, as was probably reiterated ad nauseum in the notes above, I strongly feel that one's preference between these two comes down (as it so often does with excellent gear) to taste. I suppose if I had to greatly oversimplify and tag the comparative sounds of the WA22 and M8 with pithy labels, I'd say the M8 is generally more technically accurate, while the WA22 is generally more spiritually accurate. I realize 'spirituality' is a poorly defined concept in this context, but it's the closest I can come in a bumper-sticker summation. And frankly, as something of an avowed solid state guy personally, I think it is very high praise to say that the WA22 is absolutely on the same level as my beloved Master 8 in many ways, and actually better in some. 

TL;DR Summary
-Excellent tonality with essentially everything
-Very pleasing, slightly warm sound
-Very articulate, not stereotypically "tubey" or overly lush
-Surprisingly good bass punch and control
-Excellently cohesive, organic sound, which just kills with a lot of tracks
-Great "pride of ownership" piece, looks beautiful
-Feels like it could survive a nuclear war, build-wise
-Leading edge transients not quite as well defined as M8 on most tracks
-Treble extension is very good, but a hair shy of the M8
-Texture, while very good, occasionally takes a back seat to a slightly smoother sound
-Temptation to slippery-slope one's way into vast tube expenditures (for me, anyway)

I hope this makes sense, and helps someone to a better understanding of some of the differences between the Master 8 and WA22. I very much enjoyed the (embarassingly truncated) time I got to spend with the Woo Audio WA22, and would again like to thank Mike and the guys at Woo for allowing us to check out their beautiful amp!!


Pros: Very powerful; strong mid-range & soundstaging qualities

Cons: Lack of agility/speed & clarity

Originally published on February 22, 2010


Note: this review is an exact cross-post from post #1 of this thread on Head-Fi, which contains some user discussion on the review that may be relevant to read: http://www.head-fi.org/t/473873/mini-review-woo-audio-wa22


Below are my impressions of the Woo WA22 from while I owned it (October 2009 - February 2010). However, while I owned the amp for that long, I should add a disclaimer that I put in only 2 weeks of actual listening on the amp. This is only my opinion of the amp and even I might disagree with my own impressions later. This is not meant to be a full-length review especially given my limited listening time and I did not compare the amp to any of its competition.

My reason for buying the WA22 was to try out a tube amp after going quite a while without one (the last tube amp I previously owned was an SP Extreme in 2007). I sold the WA22 not too long ago as I was done using it, as I prefer solid-state amps for the operational convenience.

All tubes were stock except for an addition of the Sylvania 7236 power tubes.


- Source: Plinius CD-101 (power cord: Signal Cable Silver Resolution Reference)
- Interconnects: Analysis Plus Silver Oval for XLR, BPT IC-SL for RCA
- Headphones: Sony Qualia 010, Grado HP1000/HP2, Audio-Technica AD2000, AKG K701. All re-cabled to balanced with the Moon Audio Black Dragon on the Qualia 010, APureSound V3 on the HP2 and AD2000, and SAA Equinox on the K701.
- Comparison amp: HeadAmp Gilmore Lite as a point of contrast only.

Evaluation Music

Alison Krauss - Forget About It
Alison Krauss & Union Station - Lonely Runs Both Ways
Andrea Parker - Kiss My Arp
Megadeth - Countdown To Extinction [MFSL]
Julia Fischer - Bach Concertos
Porcupine Tree - In Absentia
Shelby Lynne - Just A Little Lovin'
Orbital - Snivilisation
The Crystal Method - Tweekend
The Prodigy - The Fat of the Land

Stock 6AS7 vs Sylvania 7236 power tubes

I found the WA22 to sound ok with the 6AS7 power tubes, which I tried after getting used to the 7236 tubes first. But the 7236 tubes were a clear upgrade that I would recommend for use in almost all situations. There was a greater sense of power to the sound with them, with more overall punch and bass depth and force. The 7236 simply provided a fuller mid-range and a more direct sound as opposed to laid-back. However, the 7236 tubes raised the noise floor and generated some tube hiss - not much, though noticeable with sensitive headphones. This wasn't a distraction once music was playing. The 7236 tubes also provided more volume at any one setting and a higher gain so they weren't entirely optimal for a sensitive headphone like the Audio-Technica AD2000 as one example.

Grado HP1000/HP2 (7236 tubes)

I came away from the WA22 thinking that it may very well be a very good amp for the HP2 in particular, even though I haven't heard many amps on the HP2 (the other amps being a Balanced B22, CIAudio VHP-2, Luxman P-200, and TTVJ FET-A). The WA22 had a wider, more expansive soundstage than the Gilmore Lite ("GL" from here on out) with more space between the instrument sections, especially noticeable on Julia Fischer's Bach Concertos. It also added more body to the lower mid-range and fleshed it out a bit for a richer, more natural sound. It also better delineated multiple violins and provided more spatial/ambient cues for a better representation of the "concert hall" acoustic, in contrast to the GL which has more of a compressed soundstage.

The HP1000 did not respond much to being balanced - there was maybe some marginal widening of the soundstage and more depth to the mid-bass. However, I should add that the Plinius CD-101 is NOT a dual-differential source and instead generates its balanced output via phase inversion, so results will probably be different on sources that are dual-differential.

Audio-Technica AD2000 (7236 tubes)

Despite this headphone's sensitivity, I was able to achieve satisfactory volume control, even despite the stepped attenuator. With this headphone I noticed a number of less than optimal qualities though. The WA22 didn't have the blinding speed of the GL and trailed behind it in attacks on very fast impacts that were easily heard on the spring coil effects and percussion hits in Orbital's "I Wish I Had Duck Feet" and the similarly percussive but a lot more hard-driving "Smack My B***h Up" by The Prodigy. The GL was quicker, more agile, and had a more complete sound, with harder-feeling and more sudden impacts. For its part though, the WA22 had a more intuitive positioning of the layers with a more 3D aspect and a greater "reach out and grab it" factor, while the GL felt like it was maybe a little too tightly-wound and overly controlled especially with the attack/decay. The WA22 seemed to stretch out decays longer for a more realistic sound.

Also noticed with this headphone, the WA22 had a thicker, fatter bass than the GL, which is actually on the lean (but fast) side. Low "slap"-type bass sounded looser on the WA22 though, not as controlled as the GL. It did pulsate and throb low bass very well, but the GL had a more insistent, forward-moving bass while the WA22 didn't keep up as well. The GL also more easily captured details like vibrations on strings and drums, which were lost a bit on the WA22 (just a tiny bit though).

The WA22's extra dimensionality on the soundstage was easily noticed on this headphone even though it doesn't naturally have a large soundstage. To its credit the AD2000 does have an ability to tell you where the virtual walls are, so to speak.

Sony Qualia 010 (7236 tubes)

I love this headphone primarily for its treble response which is the cleanest and quickest that I've ever heard to date, and it does it without grating on the ears (or my ears, at least). One of my standard Qualia tests is Alison Krauss & Union Station's "This Sad Song." With the WA22, I noticed the treble wasn't as "hard" sounding and seemed to have less quantity. However, the WA22 helped to separate the instruments out from each other better with more accurate-sounding spatials. I still thought the GL's treble response was the better one though, as "hard" is an aspect that I think is probably more accurate for this recording, and the GL also helps the Qualia sink its claws over the metallic sheens better.

In balanced mode, the music actually took up the resident innate spatials that the Qualia allows for. There was a deeper, wider soundstage, with a greater enhanced "peering into space" effect. There was also cleaner separation between left & right with almost a perfectly mid-point center. Impulse response also seemed to increase a bit and there was less haze/blur to multiple simultaneous instruments. Overall the Qualia responded well to balanced mode, as instruments sounded off-center in single-ended mode.

AKG K701 (7236 tubes)

For this headphone, I engaged the impedance switch. On the previous headphones, I had this set at Lo, but for the K701, I turned it to Hi, and I did notice a sonic difference. At Hi, the K701 sounded clearer and less blurry. There was also more separation between instruments and a fuller mid-range & mid-bass with more body to the sound. Overall there was just a sense of the K701 being better driven, as it sounded a bit weak with the switch set to Lo.

I find the K701 to be the most average-sounding headphone that I currently own and in accordance with this, I detected no faults to the WA22 with it. In other words, the K701 sounded good, very good in fact, but it didn't reveal anything about the amp that my other headphones picked up. The WA22 simply drove the K701 well, and in fact drove it to very, very loud volume (past ear-safe levels) with absolutely no audible distortion. There was no noticeable added mid-range body, but nothing was subtracted either. It was just a strong, fluid sound that went well with the K701.

In balanced mode I found the soundstage to actually get a bit smaller but it became wider and more precise, with a better illusion of a center-point (not very apparent in single-ended mode). There was also better separation between the left and right channels and more depth to the mid-range and mid-bass, and also more dynamic range (especially on low-volume music). Impulse response improved too but still not to the point where the K701 sounded fast enough.

Final Notes

I did not listen to the WA22 with any other headphones and did not do any other amp comparisons - this review is only what it was, an informal comparison to the only other amp I had at the same time.


Pros: build quality, tube versatility

Cons: none (excpet you will spend lots on tubes)

I love this amp. Upgrades tubes are a must. It can soften the sound a bit - which can be a good or bad thing.

Woo Audio WA22

* Technical Specifications: Headphones impedance : 8-600 Ohms * Input impedance: 100 Kilo-Ohms * Frequency response: 8 Hz - 50 KHz, -3dB * Output: 810 mw with 6080, 2 watts with 7236 power tubes * Signal/Noise: 92 dB * THD: <= 0.3% * External dimension: 7”(H), 12”(W), 10.5”(D) * Weight: 25 pounds or 11.4 kg * Voltage: AC 110/220V, 50/60 Hz * Standard Features: Point-to-Point wiring * True balanced topology * All tubes. No semi-conductors in the entire circuitry * One 5AR4 [PDF] rectifier tube. Direct substitute: 5U4G * Two 6SN7 [PDF] drive tubes * Two 6AS7 / 6080 [PDF] power tubes * DACT CT2 balanced stereo stepped attenuator * One balanced XLR input * One single-ended RCA input * Two 3-pin balanced headphone output (left and right ch) * One 4-pin balanced headphone output * One single-ended headphone output * High and low impedance switch

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