Sibling Rivalry; The Woo WA2 vs The Woo WA6SE (review posted: update 6-3-2011)
May 26, 2011 at 7:48 PM Thread Starter Post #1 of 173


Chaser of Ghosts
Sep 20, 2008
I have been lucky enough to have both the WA6SE and WA2 side-by-side for a while and have spent the past couple of weeks listening to both amps. I should be finished the review over the weekend and will post it when it's all done. I primarily wanted to know for myself if the WA2 was inherently better than the WA6SE for the Senn HD800. I will attempt to answer that and more. Like, what are the differences and similarities? At least to my ears anyway. It's been fun anyway and I hope it's an entertaining read either way. Thanks!

May 26, 2011 at 7:49 PM Post #2 of 173


Chaser of Ghosts
Sep 20, 2008

I had this partially written once already but it somehow got deleted. Since I don't have total recall I've had to start from scratch. Yeah, yeah, I know, I didn't back it up. Oh well...

The first time I heard the transformer coupled Woo WA6SE that Jack Wu so generously sent me for the mini meet Frank I and I put together back in January I knew I had to have it. So I ended up not returning the amp and instead purchased it from him. He's clever that way. Lmao.

Before I had even heard the WA6SE many people were saying it's fraternal twin brother the OTL WA2 was better suited for the Sennheiser HD800 than the 6SE. Even though the 6SE does have two jacks. One for high impedance cans and one for low. Even though the people at the meet thought the WA6SE was a good pairing. I certainly did. But the reading persisted. 'Woo's OTL did better with the Senn than the transformer coupled brother...' Although this view isn't universal it was enough to get me thinking what the WA2 would sound like with the HD800.

So when Lee Shelly had his meet and, again, Jack was kind enough to lend his amps (a WA6 and the WA2) for fellow Head-Fi'ers to listen to and enjoy his products, I went home with another amp. This time comparing the WA2 with the WA6SE to, once and for all, know if the HD800 is better with one Woo amp or the other Woo amp. For me at least.

I would love to pretend to know all there is about triodes and the amps that use them to provide their power regulation and drive force. But I'm not an expert. So this review won't be a lesson on the technical differences between the two amps. There are other much more qualified members on Head-Fi to answer and discuss those.

What I really wanted to accomplish was to hear the two amps and not only know how they're different but find out if the WA2 was indeed inherently better for the HD800 than the already stellar WA6SE. It would be so easy to answer that question with a simple "yes" or "no" and walk away. But as we all know, life isn't that simple. Especially on Head-Fi. Plus what fun would that be?

There are several reasons to directly compare the two amps. The foremost being these amps are not only placed in the middle of the Woo lineup of headphone amps, they are priced almost identically. The WA6SE is priced at $1050 in stock form while the WA2 at $1090. A mere $40 separate the both of them. Another is to hear how different tube architectures contrast with each other. Plus, the WA6SE and WA2 just seem to beg to be examined.

For the most part this review is to see how the HD800 is with each of the two amps. I have the Fang's planar headphone the HE500 from the loaner program also. I will place some notes at the end of sections about the HE500 but won't do a full report. I also have the Shure 840 but I haven't spent that much time with them and the Woo amps.

So here it is... Please enjoy:

This is how my system has been set up during the test:

Laptop>WinXP>iTunes>lossless>Nordost Blue Heaven USB>Cary Xciter DAC (Nordost power cable)>Nordost Blue Heaven interconnects>Woo WA6SE/WA2 (Jellyfish power cable)>Sennheiser HD800/HiFiMAN HE500/Shure SRH840

The only variable in the equpiment is the change between the two amps. All the rest of this comparison was done with the above constants.

All of the direct A/B listening was volume matched using pink noise at 81db +/- 0.5db as that's as accurate as my Krap Shak meter is. For general and extended listening the volume was variable but my impressions are based over long periods of time and I usually listen at pretty much the 81db level anyway. Sure I have times when I want to crank it up or turn it down but I'm not going to account for every single listening variable. It's not practical. Also, having listened to both amps over extended periods of time, I have gotten to know each of their own characteristics and have to taken that into account.

The Woo WA6SE will have the stock rectifier and tubes throughout the "contest". According to Woo's site the WA6SE has 2 watts @ 32Ohms and 1300mW @ 300Ohms. The Woo has two jack inputs. One for low impedance and the other for high. I'll use the "High" jack for the Sennheiser HD800 throughout. It has two sets of RCA inputs.

The Woo WA2 will also have the stock tubes. According to the Woo site the WA2 has 310mW @ 32Ohms and 640mW @ 300Ohms. It has one headphone jack. It has four sets of RCA inputs and an RCA preamp out.

I will use the stock tubes for both amps because there are too many variables and combinations to account for to decide on which tube compliment to go with. The WA2 only came with the stock tubes also and I didn't think making an investment of tubes for the amp was cost effective for me. Plus I wanted to be fair to both amps in this overview. Also, the predominant personality and characteristics will still be within each of the amps using the stock tubes. So take it for what it's worth. Yes using different tubes can effect soundstage, bass, mids and the highs. You'll just have to judge for yourself how different tubes will change them for you. Throughout the test understand that my findings are predicated on a stock setup and based on how I interpret that.

Please also know that all of my finding are just that, my findings. I am trying to be as objective and with as little bias as possible. Understand that everything is still my opinion only and subjectivity is still a part of the process. I hope everyone realizes all of this because I don't claim any of my discoveries as facts. Thanks.


What is there to say? They're both gorgeous and are definitely born of the same parents. The WA6SE gives a slightly chunkier and thicker appearance while the WA2 has a thinner and wider stance. How can you go wrong with either?


I've always felt that the predominant foundation of an amp's quality was how quiet it is. A high or low noise floor sets the stage for a good deal of an amp's personality. A totally black backdrop seems to make the music flow effortlessly into space. Micro details pop out and additional textures can be heard.

Although I haven't found either the WA6SE or WA2 to be quite as quiet as some solid state amps, they do a very commendable job. During quiet passages in the music there seems to be a very slight noise floor with each amp and falls just short of a stark black backdrop.

On the Woo site it states the WA6SE has a S/N ratio of 93db while the site states the WA2 has a S/N ratio of 95db. That would suggest the WA6SE is a noiser amp. That's not been my experience. Well, not totally. I'll explain what I mean by that in the dynamic range section. In the whole, however, the amps are very quiet while not being the last word in black.


If dynamics and dynamic range is defined by the differences or perceived differences between the quietest passages and the loudest passages within a song or music then we're on the same wavelength. If you're using a different definition then I don't know what to tell you.

This is an area that I'm very careful to match volume levels. I check and recheck just to make sure both amps are equal to be as certain as possible I'm hearing what I'm hearing.

To me the WA2 is a naturally dynamic amp. What I mean is that the dynamics seem real. If I were at a concert hall listening to classical music with only the venue's acoustics doing the amplifying, this is how I would expect the music range to sound like.

The WA6SE, in turn, comes across as a bit more compressed. All the music seems to be closer in volume. The whispers and bangs don't seem as far apart. When I experienced comparing the WA6SE and the beta22, I felt the WA6SE wasn't not as dynamic. Different tube combinations haven't really effected the dynamic range so I know it's the 6SE itself that has a bit less dynamic contrast than several other top amps. Including it's sibling the WA2.

When I listen to Pink Floyd's songs "Echoes" and "Shine on You Crazy Diamond" and Tchaikovsky's "1812 Overture" you get a good sense of the disparity between quiet passages and more explosive ones.


Even though this section is in the middle of my review it's the section I am writing first. Why? Because it's the one difference that I can hear between the two amps that, to me, is the most obvious. Sometimes it's a benefit being able to listen to both amps back-to-back. Sometimes it's a bit of a curse. Hearing just one of these amps could have you walking away with a differing impression if you hadn't heard the other.

When I compared the WA6SE to the beta22 I came away thinking the 6SE had one of the best staging and imaging I had heard from any amp. Before I had the opportunity to listen to the WA2 I had expectations of it surpassing the 6SE. Maybe if I had never heard the WA6SE, the WA2 would have been the best I had heard. I can't be sure. But, to me and my ears, the WA6SE has proven to be among one of the best at portraying a soundstage and imaging the notes within their places.

Don't get me wrong, the WA2 does an excellent job. Especially at imaging. The placement of the instruments and vocals on the WA2 seems spot on. Until I listen through the WA6SE. The 6SE seems to have a bit more controlled distribution.

The 6SE, though, has a more expansive soundstage. Although I am using the already grand staging of the HD800 for most of this comparison, the 6SE's soundstage is especially a benefit for headphones that are, by their nature, more closed in. The Shure 840 (not the best match for the WA2) is one example.

When listening to "On the Run" from the 30th Ann of Pink Floyd's DSotM, the running footsteps seem to be coming from a further distance and running further away while using the WA6SE compared to the WA2.

"The Afternoon: Forever Afternoon (Tuesday?): Time to Get Away" [Tuesday Afternoon] from the Moody Blues' Days of Future Passed has a more ethereal quality to it from the 6SE when directly next to the WA2. The music seems to float as it was intended to.

I'm not saying the WA2 does a poor job. Not in the least. Not at all. The 6SE just has an added dimensionality the WA2 doesn't. I know I've used this song in previous reviews but if you listen to "Ride Across the River" by Dire Straits off Brothers in Arms, the contrast in soundstage really hits home. You feel as if you're sitting at the edge of a river with the chirping crickets surrounding you. It's that eerie good.

*The HE500 has a smaller soundstage than the HD800 and, in turn, brings the two Woos closer together. there is less contrast but the 6SE is still the king.


I believe this is one of the key areas that defines and differentiates the two amps. The WA2 is a more polite amp that mellows the leading edge of the notes and blends each note together. Also the decay at the end of the notes are a bit elongated. This gives a relaxed and flowing sound. I think this, in part and parcel, is what gives a tube amp the "tubey" sound. There are few, if any, sharp edges. Everything seems rounded off with the WA2. If the crispness of digital sound isn't your cup of tea but are forced to have a digital front end then the WA2 is for you. Even with a headphone like the HD800 the WA2 come across as soft. To some, though, this laid back nature could seem slightly blunted or slow.

In turn, the WA6SE approaches close to, but short of, solid state levels of speed. There is a nice leading edge of the notes without being too sharp or creased. The decay at the end of the notes are shortened off when you compare it to the WA2. Each note is it's own entity without being disconnected to the rest of the music. Although the WA6SE doesn't have the warm and fuzzy feeling of the WA2 it's neither analytical nor cold. It's takes just enough of the edge off the HD800 without losing much of the headphone's nature. That said, if you want a more prototypical tube sound the WA2 is better suited.

If you play Bob Marley's "One Love/People Get Up" off Legend you can really hear the difference. Especially in the percussion. The contrast isn't very subtle. The WA2 sounds more chilled out while the 6SE more lively.

*The very fast paced HE500 doesn't really change how the two amps react so the above applies for the planar too.


The WA2 seems to eschew some micro detail for overall musicality. I have felt that, at times, it has a bit of veil to it as a consequence. I'm not saying the WA2 is a thick wool sweater but if you're a detail freak the WA2 isn't going to be the amp that will pick up the two flies on the wall at the time of the recording kibitzing about luch. The WA2 does seem to gloss over the most minute textures.

Again, the WA6SE falls just shy of solid state performance at extracting details. The HD800 is a magnifying glass for details. The WA6SE allows the HD800 to do it's job with barely any interference. All without being analytical or etched.

*The HE500, being richer and less detailed than the HD800, has a more laid back sound and just doesn't have the detail with either amp. It seems to cope with the WA2's less revealing nature better than the HD800.


I'm not sure if the slightly more clear WA6SE or the more flowing personality of the WA2 is better with the HD800.

The more energetic 6SE and it's speed does make the music clearer and more crisp. To my ears there is a cleanness that it has over the WA2. Not on the level of solid state however. There is a touch of warmth to it that reminds you you're still listening to a tube amp. But compared to the OTL it has more sparkle.

The fluid WA2 may homogenize each of the individual notes more than with the 6SE but it does have much of the sound analogue lovers covet so much. What could potentially win you over is the tone. The richer tones adds a sweetness that is fun to your ears.

I think Mozart's Violin Sonatas, because they are simple yet beautifully unadorned tunes, really reward a transparent amp.

*The HE500 is warmer than the Senn and plays well with both amps.


Simply put the WA6SE extends further up the ladder than the WA2. The 6SE's highs are also more prominent than the more relaxed nature of the WA2. Both are very refined and there is no sizzle on well recorded songs way up. The 6SE is more lively while the treble is a bit more flat with the WA2 using the HD800.

The WA2 is more forgiving of poorly or hotly recorded music than the 6SE. The 6SE tends to reveal more of the brightness but never appears brittle. There seems to be a cleaner sound to instruments like the triangle played through the 6SE than the slightly more muted WA2.

If you have ever though the HD800 is too bright or has a spike at about 6kHz, both of these amps help quell that. The WA2 even more so than the 6SE. This is where I feel that when people say the WA2 is a better match for the Senn they are, at least in good part, talking about how the WA2 tames the HD800's treble. That's for you to decide as I feel the WA6SE also handles the treble of the HD800 terrificly with an added sparkle the WA2 doesn't. All without adding the glare.

Boston's intro to "Foreplay/Long Time" is a good song for testing treble reactions. Of course I have to fit in a Pink Floyd plug so I highly suggest you push play and listen to the guitar solo on "Hey You". You know you want to. :)

*The HE500 seems to have a flatter treble response than the HD800. Although the HE500 extends as high it seems a bit sweeter. The WA2 really handles the highs with refinement while the WA6SE still has a bit more sparkle.


Mids are where all the music is supposed to live right? Is it any surprise these two tube amps have pretty stellar mids? Listening to the mid frequencies from either amp are what tube amps are all about.

Follow my logic with the WA2 for a moment and I'll try make sense with what I'm about to say. The WA2 is the most mid centric of the two. It has rich sweet mids. It's mids are thoroughly laid back and relaxed. I think it's because the highs and bass are pushed back further with this amp as compared to the 6SE sibling. When you envision in your mind what a tube amp should sound like, this is the amp. Laid back, sweet and rich.

The WA6SE's mids are a bit more energetic than the WA2. I believe because the response is flatter compared to the WA2 the mids of the 6SE aren't as featured. Don't mistake the mids as being thin or hollow. Not in the least. It is certainly more solid state sounding than the WA2 but no-one will confuse the mids on the WA6SE as a solid state amp.


Below around 30hz both amps extend deeply and are about the same with the WA6SE a bit more detailed. To my surprise, however, the 6SE was more impactful at about 50hz and up through the bass band. Listen to the intro of The Beatles "Come Together" and it becomes apparent the 6SE has more slam to it. Not overbearing mind you. Nor does the 6SE's bass ever intrude upon the mids in any way. The WA6SE also has more control and texture.

The bass of the WA2 is hardly thin or lacking. The slight bloom over the 6SE gives the bass a sense of warmth to compensate for the bit less impact over it's brother. It is slightly more single noted than the WA6SE though.

"Rev. 22:20 (Dry Martini Mix)" from Puscifer's "V" is for Vagina album has some nice bass to test out both amps. Actually the whole album is good for bass extension and impact. "Trekka" and "The Undertaker" are also good listens. One song I use for bass definition is Pink Floyd's "One of These Days" off Meddle. The dueling bass lines really show the difference between the more textured 6SE and the slightly added bloom with the WA2.

*The HE500 has more bass impact than the HD800 while being almost as controlled and textured. It's also a bit warmer so what happens is the bass between the two amps isn't as far apart as it is on the HD800. That's not a bad thing. The bass response on the 6SE and the 2 sound excellent and very well extended.


Pick your poison here. Do you prefer texture over intimacy? It's funny how one's perception of something can change based on their perspective. What I'm about to say is almost what I said about the WA6SE vs the beta22. Except in reverse. The WA6SE has more vocal texture than the WA2. You can hear more of the timberal and vibrado changes in a singer's voice than you can with the WA2. The WA6SE still maintains an intimacy but when doing an A/B with the WA2 you can notice the difference. You can hear all the raw emotion when Kurt Cobain is singing "Something in the Way" on MTV Unplugged with the WA6SE.

The WA2 doesn't have the same fabric it's family member has but does sound more personal. Again, the WA2 is more relaxed. It's it's nature after all. Who am I to fight that? Nirvana's "Rape Me" (In Utero) highlights how close the WA2 makes Cobain seem to be singing.

After both amps are turned on and properly warmed up (about 10 minutes) they both are excellent at taking the sharpness off of sibilants. Which, to me, is always a welcome thing.

One of my favorite female vocals comes from Janis Joplin's heart-felt song "A Woman Left Lonely". It's one that could possibly make you understand why she is so beloved. Play it with either amp and you'll be swept away.

*The HE500 add a fullness to the vocals with both amps. Even more so with the WA2. Almost like it sounds a semi-tone below the HD800. I think it's more a product of the headphone than the amp. Remember that the staging of the HE500 is closer than the expansive HD800. Going back and forth between the 6SE and the 2 shows that the 6SE is a bit more revealing of vocal variations.


The WA2 is a tube amp. Pure and simple and it doesn't apologize for that in the least. Nor should it. It's a very smooth amp. It's laid back and relaxed when compared to the 6SE. I hate to use the term "organic" to describe an amp, but for lack of a better word, I'll say it. The WA2 has a lot of flow to it. It also has a richer tone. The one thing is that it might come across as a bit duller than the 6SE also. Although it has a bit more dynamic range than the transformer couple brother it seems to have a bit less energy throughout. I know it might seem counter intuitive to say that but it's what I hear. Let me try to explain. Even though the quietest parts and the loudest parts within a song are further apart in perceived volume with the OTL WA2, there is less energy in each note because of how much more laid-back it is.

With the Woo WA6SE there is a warmth that surpasses that of almost any solid state amp. More cohesion than the hybrid tube amps I've heard. What I think the WA6SE has is balance. Balance between that of tube fullness and bloom and the solid state clarity. The 6SE has an energy that is missing with the WA2.

There are many differences between these two Woo brothers. The WA2 would be the more responsible and studious brother while the WA6SE is the wild child. Other than a similar aesthetic personality I don't hear what would be thought of as a Woo house sound. Except for the sound of two extremely high quality amps.

In the beginning I asked the question "Is the OTL WA2 inherently better for the HD800 than the transformer coupled WA6SE?". I would have to say, in my opinion the WA2 isn't better. Nor is it necessarily worse. Both amps will and do drive the Senn HD800 to it's full potential. They both make the HD800 sound like the amazing headphone it is. They just do it in a different way. I also think they both take, to one degree or another, the edge off of what some think the Senn has. The choice really is yours. Do you want a tube amp that looks like a gorgeous amp and has that sweet sound to it? Pick Woo's WA2. If you want a smart looking amp that has more of what a solid state amp offers while still giving you the taste of the tube character then Woo's WA6SE might be the option you seek. I think saying the WA2 is superior than the 6SE for the HD800 is a myth. Listen to Tool's "Third Eye" on either amp and I doubt you'd be disappointed.

*The HE500 is very well suited to both amps and pairs extremely well with the WA2. In my opinion, maybe even more so than the HD800 does. That's not to say the WA6SE is a bad choice. Nope. It's actually one I would happily live with without remorse. It's just I think the WA2 is stellar with the HiFiMAN planar.

Thank you for reading my little review.


I borrowed the LCD2 from a fellow Head-Fi'er and have spent a little bit of time listening to it with both the WA2 and WA6SE. I won't write a full blown review because the overall character of the two amps still is valid. What I'll attemp to do is just go over some points that are specific to the LCD2.

The one thing I noticed was the difference in sounstage. The LCD2 isn't know for it's vast soundstage. It does, however, improve with better amping as I've experienced with all my experiences with the Audeze. As I've mentioned before the WA6SE has wider staging than it's brother the WA2. This doesn't change with the LCD2. That said, the WA2 does not sound like it has poor staging or have a problem powering the LCD2. I've heard the LCD2 under powered before and the soundstage collapses. This is not the case with the WA2. It just isn't as expansive as the WA6SE. The imaging is still excellent with both amps.

I think the LCD2 is a pretty laid back headphone. I also think when it's coupled with the already relaxed OTL WA2 it comes across as a bit TOO relaxed. The music just seems to lose a good deal of definition. I won't say the WA2/LCD2 pairing is sluggish and there may be some out there that like how relaxed it is. But, to me, it's too smoothed over. Attacks and transients are very well blended together.

With the WA6SE sounds like it has more defined notes with the Audeze. I actually think if you like an analog sound this is not a compromise.

Another area that I wanted to point out is the volcals coming from the WA2 when the LCD2 is plugged in are down right sweet and sultry. The LCD2 volcals are already well known and the WA2 really plays this aspect up. What you lose in ultimate texture with the WA2 makes up for the pure sexiness of the vocals.

That said, I think the WA6SE gives a more balanced and, perhaps, realistic presentation of singing. There is more texture and it doesn't exaggerate the strength of the LCD2.

I think the WA2 and LCD2 combination is more like a charicature of what an analogue and tube setup sounds like. I will freely admit though that I, for one, don't have NEARLY the experience with tubes and tube setups as other Head-Fi'ers. Also, I have voluntarily admitted that I prefer a more solid state sound. Having said that, I think the WA6SE takes the strengths of the LCD2 and compliments them well. I think it adds structure where the WA2 is more relaxed with the LCD2. I think the WA6 add needed energy where the WA2 is soft. Yes the treble is extremely smooth with the the two 2s together (try saying that three times fast). But I think the WA6SE is just as refined with more power up top. Another strength of the LCD2 is it's bass and the WA6SE's bass is more impactful while not overpowering. The WA2 is a bit more, dare I say it again, relaxed.

I hate to make a direct judgement with the LCD2 and amp choice. In my main article I tried to remain as objective as I could without being overt. This time I just feel the WA6SE is a better choice for the LCD2 vs the WA2.

This isn't hate for the WA2. I think the HE500 is an excellent match for it and the HD800 is a great choice with both amps. So there is no bias shown against the WA2. I just feel the LCD2 isn't the optimal match. If you want all of the strengths of the LCD2 and want a tube amp I believe the WA6SE is a terrific choice.
May 26, 2011 at 11:37 PM Post #4 of 173


Headphoneus Supremus
May 24, 2006
Awesome. Hope to hear your opinion for it will be a valuable one since you had them in your house. In my brief listen, I easily preferred the Woo WA6SE. 
It's probably because the WA6SE has an output transformer and a rectifier tube. Personally I am a lover of output transformers and I love the sound of rectifier tubes. IMO, the rectifier tube can make a tonal difference.
May 27, 2011 at 10:35 PM Post #6 of 173


Nov 28, 2006
Count me in, subscibed!
May 28, 2011 at 9:03 AM Post #9 of 173


AKA: MrSpenkalink
Feb 28, 2011
I enjoy your reviews baka1969 so I'm looking forward to this comparison of two amps that I was giving serious consideration to acquiring not all that long ago. 
May 29, 2011 at 9:36 AM Post #10 of 173


1000+ Head-Fier
Feb 15, 2010
Austin, TX
Was wondering when you would do this Ross. Subscribed.
As for the LCD-2 questions, I think that was the only headphone we didn't use when comparing these two amps unfortunately. 

May 29, 2011 at 2:29 PM Post #11 of 173


Chaser of Ghosts
Sep 20, 2008
I'm sorry but unless someone has an LCD2 to loan me for a week I'm afraid the LCD2 won't be included in the comparison. The HD800 and HE500 are the two main cans I'll be using.
May 30, 2011 at 1:06 AM Post #15 of 173


Member of the Trade: SolderWorksAudio
Nov 2, 2004

i know how it ends! haha cant wait to read your latest term paper!

.  Ross sent me a copy too.  he really outdid himself this time.  extremely thorough, and anyone who's on the fence between these 2 amps will know which way to lean.  Ross and i have the similar opinions/impressions on sonic sigs of various gears that we've both owned and i trust his ears enough that i would buy anything blindly based on his impressions if i felt it would mesh with my own needs and preferences.

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