Woo Audio WA2: My Review
Jul 25, 2009 at 6:30 PM Thread Starter Post #1 of 22


Headphoneus Supremus
Oct 17, 2005
This review has been a long time coming. It is derived from many months of ownership, experimentation with ancillary components and tube sets, and listening notes which I had to encourage myself to make (as it takes away from the time I can just sit back and enjoy).


First a little background on my amp history. I’ve progressed through a range of gear from ASL, PS Audio, Headamp, HeadRoom, and Woo Audio. I started with tubes, migrated toward solid state and eventually found myself with tubes again. I have fond memories of the ASL OTL Mk III – it was comforting and kind to my sensitive ears, very musical, albeit a little too euphonic in the long run. Its velvety magic was something I wanted to recapture.

The ASL was the first dance with tubes; the Woo WA6 came with my return from SS. Then came time to take a step up and I was conflicted as to which way to go. Given the joy derived from the WA6 – its sound, its build, its appearance, its quality look and feel – I wanted to stay within the Woo family and move up the ladder. The WA6SE had just been released and it was appealing; but at the same price as the WA2 made picking problematic. Side note – I am particularly indecisive.

Pick your poison

The WA6SE seemed more purpose-built (for ‘phones), used half the number of tubes and allowed for comparatively inexpensive tube rolling. The WA2 offered the flexibility/scalability of a preamp, more inputs, and to me was far more aesthetically pleasing (single chassis, symmetry, etc.). Choosing between the two was like asking a timepiece enthusiast “Patek Philippe or Audemars Piguet“, or a chocolate connoisseur “Valrhona or La Maison du Chocolat” – there is no wrong or right, good or bad; simply what would better suit your preferences.

I decided to send Woo Audio an email for advice. Jack’s personal preference was the WA2, hinting that it provided greater dimensional perspective and imaging and a warmer, smoother presentation. The WA6SE was touted as the powerhouse – dynamic and more upfront. Being sensitive to anything bright, prone to fatigue, and my preference for a musical, warmer character tipped the scales toward the WA2.

Just about four weeks to the day after ordering, I received the electronic shipping notice that the amp was on its way. It left on a Tuesday from NY, and by Friday I had the box in hand all the way in sunny South Africa!

The eagle has landed

Let me admit here and now, that I have not enjoyed unpacking a component as much as I did the WA2. Perhaps it was the kid-in-a-candy-store state of mind I was in, but more so the careful and professional packing job of the WA2. The amp sat cosily in its purposely shaped protective mould, with clever cut-outs for the tubes. Setup was simple too; intuition would be enough to guide even a tube newcomer though the PDF manual received by email provided some useful data on the amp, its care and setup. Ten minutes, six tubes, a power cable and pair of interconnects later, the amp was up and running. A subtle red luminescence gathered through the valves, like blood flowing through their veins, brining them to life.

In the field

My musical tastes are broad. I am open to pretty much anything save for opera and heavy (read suicidal) blues. There are a few albums which I often drift to when analyzing a component or system. The how-does-it-sound part of this review thus comprises thoughts on how the WA2 fared with these. These are not meant to be descriptions of the music (like an album review); rather, what I touch on explicitly are those parts of the sound which I felt particularly noteworthy, relative to how I have heard the music on other equipment, and attributable in part to the WA2. In terms of ancillary equipment: I used my Marantz SA7001KI SACD player feeding the amp through Zu Audio Gede interconnects, with headphones including the HD650, SA5000, K701, DX1000, D2000 and IE7.

New age music is a perpetual favourite of mine. I have a soft spot for the Karl Jenkins composed Adiemus. First up was Adiemus I: Songs of Sanctuary. The title song is a testing track, given the numerous contrasts it contains. The bass note following the brief vocal intro is capture relatively deep in the mix so as not to overpower the delicate vocals. A common sin of some amps with the track is having this insufficiently controlled and present; sounding hidden – lean or even camouflaged. Usually amps which do that also present the choir in the chorus in a bright manner; the WA2 resolves the individual voices – composed and not in any way stringent.

The almost 5-minute build up on Tintinnabulum, with a mass of strings toward the climax, can kill the ears before the track even truly starts. The WA2 does not round or roll this off – the bite and some sharpness remains but not in an overcooked manner. As above, not stringent – I did not feel myself having to raise my cheeks (like you do when something is too loud and piercing). In the chorus of the track an eclectic mix of instruments accompany the chorale; in the backdrop are two orchestral drum hits in quick succession, repeated once with every round of the chorus. You may miss it if you have not heard it before, but once you know what to listen for it becomes a vital and solid foundation to the rhythm.

In Caelum Fero is surprisingly fast-paced; and highlights one of the Woo’s strengths: having both warmth and requisite speed. Some amps can remove too much edge and attack, sounding somewhat viscous, whilst others tend to drop off sustains and decays too quickly. Fortunately the WA2 does neither to a significant degree. Overall though, it tends toward warmer sound – that is to my preference; as I find it adds to the musicality and enjoyment.

Keeping with Adieumus, on the fourth album title The Eternal Knot, Conlla’s Well is a happy-go-lucky track. It is not forgiving though; the flute can be piercing as it is recorded quite hot. On the WA2 it is upfront but clean; what I think to be naturally so. Isle Of The Mystic Lake is quite a complex piece, though deceivingly so. The reason is that the vocal/instrument mix can sound congealed. This was a good test for the WA2’s soundstage capabilities. I do not think it is the most expansive soundstage I have heard; but neither was it congested. Instruments which needed spatial separation were so portrayed. At around 1:10 the choir takes centre stage, with shakers and cymbals in the backdrop to either side. Amps with larger presentations have these more distinct with more space (dare I say “air”) between them – I could differentiate them using the WA2 (not on top of each other) though their positions were not entirely in their own space. I think, however, that interplay may be a good thing. Too much separation can result in unnatural isolation.

Whilst the above talks to width; depth is something the WA2 does manage commendably well. I can describe this trait by saying that accompanying acoustic elements come across as exactly that – accompaniments. That is, audible enough to play their part, sounding neither like they are trying to take the lead, nor fusing into the surroundings. What the amp lacks in soundstage width it makes up for in layering and dimensionality – elements are not flattened but reside in varying planes.

Doing a complete 180, it was time for some pop-rock. Red Hot Chili Peppers’ Stadium Arcadium (Disc 1 - Jupiter) gets my feet tapping each time it spins. Dani California has a 70’s synth-twang which as described in the paragraph above is well layered. It works surprisingly well with the grunge-like guitar distortion which, instead of just being a noise, had tune and texture. More importantly, it is kept in check without bleeding into the vocals which remain clean and unfazed.

She's Only 18 features drums with some thwack. The background solo guitar riff is addictive and placed to the rear right of the singer. Slow Cheetah features a similar riff but this time to the left and farther back. Both tracks have an addictive bass line which is well controlled; articulate and with fine speed. This emphasized another noteworthy trait of the WA2 – control of the lower frequencies. It has a particularly firm grip, and even with ‘phones like the HD650 and DX1000 it did not permit much overhang. The word I would use is engaging – bass notes are easy to follow, supporting the rest of the music.

Stacey Kent is relatively new to me. Breakfast on the Morning Tram was the album of choice and Ces petits riens talks directly to my mojo; there’s something about the jazzy tempo, smooth though slightly nasally vocals, and dynamic upbeat rhythm. The piano is vibrant as is the tuneful bass. This track I enjoy anytime, but particularly on the WA2 as it was both orderly/disciplined and a hell of a lot of fun. I am not sure how to describe Hard Hearted Hannah (the word “Southern” comes to mind) but it is an interesting juxtaposition to the softer tracks on this album. The contrast is portrayed well – her raspier, spruced-up vocals and the punchier piano notes in particular.

Having seen Katie Melua live, I was pleasantly surprised with her albums’ vibrancy and character. Throughout the album Pictures the music was lively; closely recreating the emotion of her somewhat deep, silky and sultry voice. The amp had warmth to keep my ears pleased and fatigue-free, without excess coloration to skew how the music should sound.

It's All In My Head is another showcase of deep bass control, especially right at the start of the track. Later on the soundstage opens up – again not as expansive as it can be, but I could quite easily hear the other instruments as they were brought into the mix. Different tonal characters of the tracks are discernable, such as the cheeky, sexy Dirty Dice which is distinctly different to the indie-pop sound of If The Lights Go Out and Spellbound and the laid back, bluesy character of What I Miss About You.

The final stop is classical. If there is one instrument that can make my hair stand on end, it is the violin. I have a long-standing love affair with it, and one of the recent discoveries I am grateful for is Julia Fischer. She plays with emotion and passion which has been known to elicit tears in grown men.

There are two tracks I want to touch on from her Russian Violin Concertos album. The first being Violin Concerto in D minor - I. Allegro con fermezza. It starts out relatively quiet and builds up progressively. The WA2 was requisitely agile, able to move with the music as it ebbs and flows, drawing you in and out. This is especially with her solo violin – the movement features slow, romantic violin which rises and recedes in volume and veracity. It is always, however, crystalline and harmonious. III. Allegro vivace is far quicker and snappier, but also happier. The violin is joined by charming flute and a deep cello with body and a beautifully warm resonance. This movement is full of dynamic contrasts which the WA2 handles with aplomb.

Off the field

I wanted to briefly touch on the amp from an ownership and use perspective. The WA2 proved easy-to-use and almost unfailingly reliable. The only hitch (and scare) I experienced was having the power LED suddenly light up when the amp was off – this occurred when removing tubes for rolling. A couple of emails to Jack had this attributed to charge being stored in the caps flowing upon having a tube yanked out the socket. Simple solution – once switched off, remove the power cable and leave for ten minutes allowing any surplus energy to discharge.

Noise floor is one of a (tube) amp’s acid tests. The WA2’s pitch black backdrop is admirable with all full-sized ‘phones I tried. High-sensitivity IEM’s did not fair as well – they exhibited a mild background hum, though only audible with no music playing.

Sockets on the rear panel are sufficiently spaced out for my cables – though I can foresee possible issues if you use overtly thick interconnects. The labelling is neat and tidy; the two silkscreened demarcations separating audio inputs and outputs are another one of those simple but noticeable touches.

A quick note on burn in: I must say that I did not perceive too much change, especially having used the stock tube complement for at least 200 hours before rolling. Two subtle changes though (which could be the amp settling, my ears settling to the amp, or placebo): mids became a little more fleshed out and full bodied; and high upper frequencies (think Sarah Brightman) settled / mellowed to a more natural timbre; becoming a little more refined and less spotlit.

Aesthetically the amp has a presence about it sitting atop the audio shelf in all its glory; looking particularly attractive basking in sunlight. The variations of textured silver and curved lines of the anodized aluminium truly capture the eye and the heart.

I am particularly drawn to the smaller details and design elements which together form the WA2. Worthy of mention are: the way the volume and input knobs, and power switch, have matte bodies but a shiny mirror-like surface; the elegantly shaped power transformer and choke covers with the grooved walls and stylish chamfer on top; the engraving at various places on the amp – power button, inputs 1 through 4, volume knob, headphone jack, each of the tube sockets, and the eponymous Woo Audio logo. These add up to make the amp look professional and certainly more “high-end” (for lack of a better word) than most other contenders, especially at the price point.

Summing up

As you can tell, I like this amp – a lot. It is, for the foreseeable future, a keeper. I have gone through a number of amps on my journey, each time trying to hone in on what it was I actually want and enjoy. The WA2 ticks more boxes than any other amp, and I thoroughly enjoy music played through it. It is not perfect – no amp is. I am sure it will also not suit everyone – each set of ears has their own preference.

The WA2 however is a very capable, flexible, dynamic amp. It does not splash excess colour on music, but does walk on the smoother and warmer side of the track and absolute neutrality. To my ears though, it certainly does the trick. It does so without being syrupy; has iron-fisted control of any headphone I throw at it, and most importantly – it communicates with me and my emotions.
Jul 25, 2009 at 6:30 PM Post #2 of 22
I think I am finally in a position to post some impressions on the pairing of the WA2 with the HD800. The 'phones now have around 100 hours on them, about half of which was pink noise, so I feel they are sufficiently burned in.
  1. Firstly, during initial listening sessions I had the volume quite high - around 11 o'clock on my Woo WA2. I am not sure if that was because of the many months of IEM listening where one gets inherently accustomed to higher volumes (I sold my full-sized headphones about 6-months before the HD800's and had been using the Sennheiser IE7 until now), but I feel myself dialling back quite significantly now. Across the board with various genres, I find myself at around 9, or 10 max.
  2. I attribute much of this to the sheer level of detail extracted by this headphone (and amp), even at very low volumes. Many 'phones I have heard hide/disguise much of the detail until a certain volume level is reached; and often once you reach a point higher than their "comfort zone" they start spotlighting frequency ranges and details start overpowering. I tend to think of this phenomenon, graphically, as an exponential increase. With the HD800 it is amongst the most linear I have heard, on par with the Stax SR-007/SRM-717 and (from memory) close to or at the same level as the AKG K1000.
  3. The AKG is also the immediate can which comes to mind for comparison in another aspect - liveliness. There is a special attribute which I only previously heard with the AKG which I cannot fully describe or firmly put my finger on, but the HD800 shares this. It is this presence and vivacity which makes each element of the music real. I suspect this is the "speaker-like" presentation, where if you close your eyes you can see the instruments on a stage in front of you in their own space. They do this though whilst still working cohesively together so as not to make them sound isolated (or give you sea-sickness) - I feel the perfect term for this is "poised".
  4. Admittedly, I do not feel it has the same dynamics as the K1000, at least not with the WA2 and using the source, tube combo, etc. I used. This may be due to a) the open baffle design of the AKG; b) the ear-bleeding dB levels the AKG could so easily reach; or c) the WA2 being inherently smooth and slightly laid back. Perhaps an amp with more "balls" would give the HD800 more dynamic capability but I feel it would also introduce possibility for fatigue, as I had experienced with the K1000.
  5. I had this when using the K1000 with different amps....the Almarro A318B with its 6C33C's was amazingly dynamic with the best bass I heard from the AKG, but was too bright for long-term listening pleasure. The PrimaLuna Prologue with its euphonic EL34's was far to my liking, but I could understand people think that, for them, it lacked dynamics. My sensitivity to high frequencies and disposition to fatigue though surely play a large role in this so YMMV.
  6. In regard to being forward or bright - the HD800 has an ability to be forward (and hot when required or when on the recording) but not bright in the negative sense we normally refer to. This very much reminds me of the Sony SA5000 - lightning quick, but not fatiguing. The HD800 manages, however, somehow, to be both livelier and less fatiguing than the Sony (which could sometimes sound 2-dimensional or "wallpaperish"). The K1000, from memory, did so too but could be a little too much for my ears (amp dependent).
  7. The above "lively but non-fatiguing" is proving itself as we speak whilst listening to Hayley Westenra's "Celtic Treasue" album. Unlike, say, Sarah Brightman, who's recording are often recorded too hot and seemingly mastered for a pop crowd (picture a smiley face EQ); Westenra's albums are far more natural, kept simple (3-4 naturally recorded instruments at most) so as not to overcomplicate or overpower her delicate voice. However, her voice still plays predominantly in the upper registers. The voice together with raspy wooden Celtic flute, harp, and Irish pennywhistles have tired me out on many occasion. I think this is the first time I have ever listened to the album right through and still feel fresh, sans ringing. That said, a badly recorded record will not be sugar-coated. Westenra's "Odyssey" album is, in a word, atrociously recorded and this is evident warts-and-all when listening to it.
  8. Poised, lively, but non-fatigiong detail proved itself over and over listening to albums such as the Cranberries' "To the faithful departed" which is extremely well recorded, punchy, detailed, but the guitars and drums and vocals didn't fry my eardrums. Ditto for new age music....."Songs of Sanctuary" again is an album I return to as it has so many amazing details, but inferior amps and headphones fail at presenting the complex arrangements as beautifully as they should be. The album also highlights another point - since it is a relatively low volume-level album (both the CD and SACD are like this), I need to turn it up higher than other CD's. I can do this without worry, and can easily take it to 12 o'clock and the WA2/HD800 remains natural, smooth, consistent, with a pitch-black background.
  9. I would not say bass is lacking; when the bodhrán beat on the Westenra album you feel it, and (commendably) hear the texture of the goatskin head. And on albums like this which emphasize the human voice and instruments' natural timbre, the neutrality and dynamic capability of the HD800 are noteworthy. I do think though that the HD800 is better suited to classic and light jazz / blues (softer music in general) than rock or electronic.
  10. I also initially had a worry about empty-stage syndrome (ala AKG K701 / Grado GS1000). With the music I have tried, and in this system, I am not experiencing this. This in particular with classical music (which the likes of the GS1000 was supposedly phenomenal with). I listened last night to Hilary Hahn's Bach Concertos (Deutsche Grammaphon SACD). It is a full-bodied, rich musical experience which I have heard sounding lean; even threadbare - as if recorded with excess reverb. Other systems still have congealed the individual players in the LA Chamber Orchestra accompanying her. I heard each delineated but the music remains beautifully woven together.

I am trying not to lay down superlatives or over-stretch the positives. But right now it is hard to - the HD800 is neutral, phenomenally detailed, and with the WA2 is giving me goosebump moments each evening. The warmer character of the WA2, together with its smoothness and sheer emotion is simply.....lovely.

I am tube rolling and playing around with other tweaks too, which the HD800 I find is very sensitive to. I am trying to find a tube combo and cables to share enough "truth" whilst still allowing me to listen to not-so-brilliantly-recorded albums without cringing. Right now, some black-base RCA 6AS7G's, Philips Miniwatt EZ80's and UK Mullard ECC88's are doing just that.
Jul 25, 2009 at 6:55 PM Post #4 of 22
Nice review. I'm considering on getting a WA2. Just like you, I'm sensitive to anything bright, prone to fatigue. I also prefer warmer presentation.
Jul 25, 2009 at 7:06 PM Post #5 of 22
Great job X....I was wondering when you were going to review it...

Also, looking forward to your tube favorites. I know you have tried quite a few combinations....


Originally Posted by xenithon /img/forum/go_quote.gif
The WA2 however is a very capable, flexible, dynamic amp. It does not splash excess colour on music, but does walk on the smoother and warmer side of the track and absolute neutrality. To my ears though, it certainly does the trick. It does so without being syrupy; has iron-fisted control of any headphone I throw at it, and most importantly – it communicates with me and my emotions.

Very true and very well said. It does an excellent job of controlling all sorts of headphones and making them shine.....I'm using all 4 inputs and the pre-out to my A5 speakers and have never been disappointed on anything that I have plugged into it...

Again, Great Job
Jul 25, 2009 at 7:20 PM Post #6 of 22

Originally Posted by xenithon /img/forum/go_quote.gif
I decided to send Woo Audio an email for advice. Jack’s personal preference was the WA2, hinting that it provided greater dimensional perspective and imaging and a warmer, smoother presentation. The WA6SE was touted as the powerhouse – dynamic and more upfront. Being sensitive to anything bright, prone to fatigue, and my preference for a musical, warmer character tipped the scales toward the WA2.

ahh...that explains it. thanks.
Jul 26, 2009 at 1:42 PM Post #7 of 22
Very nice review! Of all the mainstream tube amps I have not owned, this is the one I'd probably most like to have
Jul 26, 2009 at 3:04 PM Post #8 of 22
Thanks you for this well written review that actually tells alot about the product and does not just rave about how good it is. This might help people who are deciding what to buy next. I can only agree with how you describe the wa2. I find it very easy to use and I love the fact that it is auto-bias (tube rolling is very easy and I am a noob) and I LOVE the volume control on my maxx version. I am very much loooking forward to your impressions of different tubes and even more to your hd800 impressions. I would also like to know how you li9ked the wa2 with the headphones mentioned in your review, did they allhave good synergy for you?
Thanks again,
Greetings, Anouk,
Jul 26, 2009 at 5:54 PM Post #10 of 22
A beautifully written review X, the first on this forum to do justice to this relatively unsung gem of an amp in the Woo Audio product range.

Knowing the research you put into your purchase and your keen appreciation for high quality audio, I'm very glad the WA2 is still providing you with much pleasure after many months of listening
Jul 27, 2009 at 1:23 PM Post #13 of 22
Hi X

Very interesting read.

I assume that you are reviewing the WA2 with the uprated power supply and not your previous WA2. Have you noticed any difference between the two?

I am really looking forward to your reviews on the WA2/HD800.

Jul 31, 2009 at 4:00 PM Post #14 of 22

Thanks for this great review. Well written, very clear and concise, even for a non-anglophone like me.

It's funny, because I own an ASL MKIII amp with upgraded parts for the importer here in Canada.I also changed the tubes for RCA (6BQ5) and Telefunken (for the 12ax7 one). I just love the sound of it.

I recently bought Sennheiser HD800 and I think I will upgrade my headphone amp in the near future, because I'd like to make sure I get the most out my headphones.

Your musical choice is also very close to mine (I have more than 150 NewAge CDs).

When I was looking for the Senn HD800 info, I read a couple of reviews where the person used a Woo Audio headphone amp and seemed particularly pleased.

My question to you (if you don't mind) would be the following: do you think that the upgrade from ASL to Wooaudio2 is worth it or should I consider going to a higher level to hear a good improvement? If the Woo2 is enough, should I also consider the upgrade parts?If so, which ones?

Maybe it's better having the Woo2 with upgraded parts than a more expensive one stock... what do you think??

It's too bad, cause I can't listen to it first. This is why I need an advice.

Anyway, thanks for your time



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