NwAvGuy’s Objective 2 by JDSLabs and Epiphany Acoustics

April 4, 2012 | by Lieven | $100-$300, Desktop Amps | Epiphany Acoustics, JDSLabs

The biggest thing that I’m missing with the O2 is bass impact and punch. It’s funny because if you build a Cmoy with two 9V batteries you’d get a far better bass impact than you do with the O2, and a much sweeter midrange that is always the character of Cmoys like the JDSLabs CmoyBB. Another area that I question is the detail level. If we gonna promote the O2 as a technical amp (due to the superior black background), another thing that technical amps are usually good at is micro detail level. But with the O2, I would say that the detail level is not that superior from a Cmoy.

The question I have with the O2′s superior black background is if it’s indeed the result of superior circuit design or mostly just a function of a lower gain setting. I had both the Epiphany and the JDSLabs with me at one point in time (The JDSLabs later I sent to Lieven for his evaluation), and the two O2 builds differ in the application of gain levels. The Epiphany build applied an overall lower gain level on both its low and high gain setting than the JDSLabs (1X and 2.5X on the Epiphany, 2.5X and 6.5X on the JDSLabs). This leads to an even blacker background in the Epiphany amp. Of course you can ask JDSLabs to build you an O2 with the same low gain levels so that’s not really an issue, but the point that I’m making is that with a lower gain, the sound is cleaner and the background blacker (as is the case with almost all other amplifiers). However, the opposite is also true. At the high gain setting (6.5X), which is closer to the gain of a typical Cmoy build, I really don’t hear the technical advantage anymore. The noise levels are up, the black background is gone, and comparing it with the JDSLabs Cmoy I even discovered that the Cmoy has a better midrange clarity, though more rolled off in the bass (boost OFF).

NwAvGuy seems to have a very strong belief in his measurements, but one thing about amp measurements is that even the biggest names in audio amplifier designs have confessed that good/bad measurements doesn’t always relate to good/bad sonics. Of course the premise that good measurements equals good sonics in itself is largely an assumption, and a statement from Nelson Pass actually casts a strong doubt on the validity on the premise:

“It is nevertheless possible to have a product that measures well but doesn’t sound so good. It is still a mystery as to how this could be, but there it is.”

I am not saying that you don’t need to do measurements and good design practices, but relying on them alone is not enough. A good feedback from a pair of good ears to further improve the design and the tuning would definitely help.

If you’ve had the chance to listen to the AMBLabs Mini3 and the Cmoy amps, you know that both amps are very good sounding. I certainly won’t go around the web blasting both the Mini3 and the Cmoy just because it measures bad, if the fact is these two amps in fact sound very2 good. I personally have yet to hear one guy who’s heard the Mini3 and gave a negative listening impression. When I did the sub $100 portable amp shootout, I noted that while I’m not such a big fan of the Mini3′s sound signature, it was clearly the most competent technical amp of the bunch. And comparing its technicalities to the O2, I think that both amps have their advantages and disadvantages in terms of technicalities (i.e better articulation, speed, detail level on the Mini3). The Cmoy is actually, in my opinion, the most musical sounding of the three here and despite the cheap association we have with the Cmoy name, what matter is that a lot of people do enjoy the sound of it. Likewise the Mini3 also has a huge fan base, and I don’t think that they’ll start abandoning their amp simply because NwAvGuy wrote so convincingly about how his amp is superior to the AMBLabs’. Of course both the Cmoy and the Mini3 can be build in an enclosure small enough to match the iPod’s footprint, making them real portable amps. As for the O2, it’s a good amp, but not really the total knockout NwAvGuy would have us to believe.

Edit 05/04/12: John Seaber from JDSLabs’s confirmed in the comment section that all O2′s now ship with a set of stick-on bumpers (feet), so the O2 can’t slide around. “Headfonia’s O2 sample shipped before we spotted this inconvenience…”

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http://twitter.com/Brian_K3 Brian Fu

In my opinion the problem is those inexperienced people who thought that the O2 is more than what they paid for. The second part is important as it actually applies in all aspects of our life.

It’s amusing isn’t it? For something that has an “Objective” moniker in its name, the people who defend it sure don’t strike me as having that characteristic to me!
- l_e_e
  
  In my opinion your comment is insulting a lot of people you don’t even know and should be removed including your right to post.
  - http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
    
    Is this against the website’s Terms of Use?
  - http://twitter.com/Brian_K3 Brian Fu
    
    I see that I had touched a nerve.
    
    Look, I will say this again as it is obvious that my intent was lost. You are getting a battery-powered op-amp driver with the O2 and that is EXACTLY what you are going to get performance-wise. The O2 is not going to somehow magically outperform a Zana Deux, a β22 or a GS-X. It’s just not going to happen.
    
    That’s as silly as me buying a Honda Civic and expect it to outperform say, a Mercedez-Benz C200 Kompressor.
    - http://ancientwisdom.pip.verisignlabs.com/ AncientWisdom
      
      “You are getting a battery-powered op-amp driver with the O2″
      So I understand that you claim to be well versed in audio design? maybe you can try and design a better amp.
      Regardless there is proof on the internet that the O2 is transperant, no amount of mambo jambo you write here (“magically outperform” as if there is need for magic for this to happen) is going to change that, if you think it is not transparent, i.e. discernable from other “amazing” (transparent) amps with impresseive names etc. prove it by distinguishing between them in a blind test.
      As long as you do not do so your words are air.
    - Cola Bear
      
      LOL you cracked me up so bad my sides hurt!
      
      “You are getting a battery-powered op-amp driver with the O2″
      You couldn’t possibly have written this with a straight face. First off, battery power is the quietest source. Why do you think Naim (well regarded audiophile product manufacturer), among others, makes/made battery-based gear? Isn’t highly-touted AMB Mini3 battery-based with op-amps? Even Violectric (Liked by Mike & Lieven) uses op-amps. Your point is meaningless. Have you no understanding of the whole music production chain? How many op-amps, whether battery or AC powered do you think all your music went through? Hundreds, if not thousand(s), many different types and makes.
      
      The O2 doesn’t need “magic” to beat many other more expensive amps. Here, straight from AMB’s web page (Re: ß22)… “The all-discrete (no integrated circuits), fully complementary and cascoded topology, high-current MOSFET output stage, full class A operation and carefully tuned operating points vanishingly low distortion (emphasis mine), high speed, wide bandwidth, low output impedance, and high output power. All elements of the design were critically examined to create an amplifier that performs as well on the test bench as it does with music.” So, a much less expensive “battery-based op-amp driver” beat the ß22. Google for yourself.
http://www.theideate.com/ Gorboman

It’s like seeing another form of battle between fanboys. Mac vs PC, Android vs iOS, and now this.
- http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
  
  Macs are clearly better.
http://ancientwisdom.pip.verisignlabs.com/ AncientWisdom

Your comparison is completely invalid as the headphones you speak of have different presentations (and these are ok to be subjectively preferred).

The amp in question was built to be transparent. If this was done successfully then it is impossible for it to be thin and lacking bass etc. and there shouldn’t be any subjective preference to it over other transparent amps.
If not transparent then this would be of interest but that does not seem to be the point the review is trying to make.

*grammer
http://profile.yahoo.com/FE45QONAAMO5BO7DBDF34H6JBA Inter Cambio

It might sound like a bit of a wimpy cop-out, but I genuinely don’t see why us audio enthusiasts need to be strictly divided into to warring camps – subjectivists and objectivists. I for one enjoyed the review as always – I enjoy reading Mike and L’s comments and I also like to see the measurements too if possible, is that wrong?

The way I see it, Headfonia isn’t anti-measurements at all. The difference between this site and NwAvGuy’s blog is simply that here the measurements are done by ear. Like a reading an opinion of an artist’s album then you just have to be aware that the reviewers have their own taste in and experience of music, and to realise your own perceptions of the same kit may well be different. I don’t get the feeling that this site negatively reviews cheap gear for the sake of their sponsers, some good examples to the contrary are the PA2V2, JDSLabs Cmoy, Fiio E10.

Purely for your own interest (or perhaps also for charity), rather than to appease the rabid objectivists, I think it would be great for you guys to do some kind of experiment comparing the O2 with a more expensive amp that also has low output impedence. I think but I’m not certain that the Violectric qualifies, and it would be fun to use some LCD-2s or HD650s for the test. I personally think that measurements can tell you everything, so long as some of those measurements are done with your ears!
- l_e_e
  
  >The difference between this site and NwAvGuy’s blog is simply that here the measurements are done by ear.
  There are at least two things wrong with this:
  1) NwAvGuy (and others) also did comparisons by ear with the DAC1 for example.
  2) Are you sure that here the “measurements” are done solely by ear? (see the “What We Hear” article).
  - http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
    
    Why is it wrong to have a subjectively based headphone review site? If I wanted only measurements, I’d go to Nwavguy’s site.
    
    Seems pointless to try to change the direction or discredit this website. Mike and L are doing a great job and many appreciate it.
http://www.facebook.com/marco.bardoscia Marco Bardoscia

May I ask which recordings have you used for reviewing the amp? One may naively think that a neutral amp is more suitable for reproducing some genres (classical, acoustic jazz) than some other ones (rock, electronic). Could this wild guess be correct, at least to certain extent?
http://www.facebook.com/donunus Don Vittorio Sierra

NwAVGuy is quite powerful. Think about it guys, everyone is arguing about a sub $200 amp because of his strong views LOL. I say buy an O2 for yourselves if you really want to know if its good for you or not instead of joining the o2 argument wars before listening hehehe.

I for one am intrigued by the infamous o2 but I can hear the differences in the sound between products that are typically called snake oil like different power cords or even reversed interconnects so I myself really want to listen for myself if the o2 really makes the music flow without coloration.
- alejandro vidal
  
  have you tried listening to those differences without knowing which component are you listening?
  - http://www.facebook.com/donunus Don Vittorio Sierra
    
    Like I said, I’m not joining the argument yet since I haven’t bought the o2 yet
    - alejandro vidal
      
      I meant the differences between power cords, interconnects, etc.
      - http://www.facebook.com/donunus Don Vittorio Sierra
        
        Oh yes I have actually pinpointed which wires were which in a blind test in fact I have pinpointed if a certain interconnect was reversed or not. I get confused though if one channel is reversed and the other is not because the overall sound with the weird left to right difference throws me off.
http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer

edit
- http://www.facebook.com/donunus Don Vittorio Sierra
  
  It makes me want to buy an o2 just to see what all the fuss is about
  - http://twitter.com/Brian_K3 Brian Fu
    
    It is pretty good for what it is but it ain’t replacing my β22 anytime soon.
    - http://www.facebook.com/donunus Don Vittorio Sierra
      
      LOL
orta03

It’s amazing how many of you seemed to be surprised that Mike & Lieven did a subjective review of O2 without measurements, blind tests, using the scientific method, setting a hypothesis first, laboratory equipment, PHDs in physics and mathematics, and Data from ST(Star Trek):TNG. Instead, electing to use only their*gasp* ears?! Shocking! It’s only the way they’ve reviewed every other piece of gear on the site.

Seriously, where was all the howling and crying when Mike gave a lukewarm review of the very neutral(and rather expensive) Meier Concerto and StageDAC? If one had been following Mike site at all, he stated quite a few times that many audiophiles(you know the people who like to enjoy music) and himself included prefer warmer sounding gear. That is a major reason(among others) why tube amps have maintained their popularity. Knowing that, is it surprising that Mike & Lieven were not completely enamored with the O2?

That is not to say, neutral sounding gear isn’t good. Far from it, as many(audiophiles included) prefer neutral sounding gear. I apologize for my comment’s tone, as I rather not be involved in any arguments or flame wars. What irks me is the “my way or the highway” approach of some of you. Not every person prescribes the NwAvguy’s philosophy nor should they. In this audio hobby of ours there are quite a few ways for one to reach audio nirvana. That’s the good thing about it, there’s something for everyone(and every budget).
- http://twitter.com/Brian_K3 Brian Fu
  
  That is because the gear in question is the holiness O2 borne out of love and sacrifice from someone whose first move to promote his philosophy is to attack and slander established DIY designers in various internet forums.
  
  If anything, the O2 is a perfect testimony on how devastating FUD marketing can be if executed properly.
  - http://openid.anonymity.com/wrampc Guest
    
    I love how the Mini3 review is apparently “slander.” As NwAvGuy himself put it, various people still seem to be convinced that he tested a Mini3 built out of parts from a toaster oven, and the measurements were all sabotaged, and that if AMB somehow “got lucky” with the measurements (?) that they should be allowed to stand, that AMB is experienced and NwAvGuy could not possible appreciate the physics-defying unmeasurable magic subtleties of three channel design…
    
    It is best not to attack someone for slander by slandering them.
  - Cola Bear
    
    I do not think the NuForce µDAC-2 nor the Schiit Asgard qualify as “established DIY designers”. Those are commercial companies with no excuse for the product errors they made. As for AMB, their product(s) may be DIY or purchased whole. There was no slander or attack. Those products were simply shown to be either dangerous to headphones (Asgard) or not meeting posted specifications.
    
    If you purchase something, don’t you expect it to perform to the manufacturers specs? What if your new AMG 591hp V-8 roadster only reached 115hp and 55ft-lbs torque? Would you not be outraged? If the manufacturer said “Well, our test battery must have been overcharged and we got lucky but we measured what we posted” would you not be disgruntled?
    
    In the expose of the various products, where they did have some good points or performance, it was stated. This is not slander. Look up the definition before throwing words around. Also, your comment on FUD (Fear, Uncertainty and Doubt) is not correct either. Since the specifications of the O2 are very detailed, there is no FUD as any consumer can be assured of the quality. FUD enters in when you cannot rely on your manufacturer to be honest in their stated specs.
- l_e_e
  
  > use only their*gasp* ears?!
  Ever heard of bias? Guess not.
  
  @Brian: Why all the hate? Do you feel threatened by the O2 because it performs better than the b22 in terms of distortion as measured independently on H-F? Or because your b22 was probably 10x – 20x as expensive? *giggles*
  - http://twitter.com/Brian_K3 Brian Fu
    
    Let’s get this straight. I honestly think that the O2 by itself is a great product, given what it is. I find it to be an improvement compared to a vanilla CMOY as pictured in my profile image.
    
    It’s just a shame that its some of its proponents tend to be on the… narrow-minded side, suffice to say. Just look at how your lot came here to bash Mike’s review just because it’s slightly less than stellar. Heck, if you actually take your time to read the review it actually offers a pretty balanced viewpoint compared to the usual 6moon “everything sounds good” prose so the vitriol is frankly unreasonable.
    
    Additionally I find the designer’s move to discredit other more established DIY designers (using measurements on an improperly-built unit should I add) before shamelessly promoting his own design screams of an utter lack of class and ethics.
    
    And regarding the β22, I don’t see the need to flaunt it everywhere. After all, great designs establish themselves by the virtue of merits alone without the need of a select bunch of people to artificially inflate its reputation in the Internet.
    
    And that’s that. Thanks for the space Mike and Headfonia, I haven’t had this much fun commenting on your reviews. :p
    - l_e_e
      
      Talking about narrow-minded, you assume that NwAvGuy’s mini3 was somehow broken but for example Shike measured a professionally built Mini3 with a dummy load (a simple resistor) and got results very close to NwAvGuy’s.
      
      Maybe his way of publishing those results were not the right way, but this doesn’t change that some (?) designs of that “established DIY designer” are average at best. What I find borderline fraudulent are the claims and “specifications” on the mini3 page, but I guess you gotta be less narrow-minded to see that.
      
      You see, you’re not the only one who can write condescending comments and enjoy oneself.
      - http://ancientwisdom.pip.verisignlabs.com/ AncientWisdom
        
        Honestly I applaud your perseverance, my reaction when I saw his comment was to roll my eyes and get on with my life… When the narrow mindness claims come out you know it’s time to gather your stuff and move to another town.
        
        And PS Brian we didn’t “come here”, we were always here, (presumably) just like you.
      - http://www.headfonia.com/ L.
        
        All you guys should get a room and make up
      - http://ancientwisdom.pip.verisignlabs.com/ AncientWisdom
        
        L: you are LIKING this aren’t you?
      - http://www.headfonia.com/ L.
        
        Not really actually. I’ve just had it with all the negative, attacking comments. No product should have this effect. We all love audio in our own way, just accept that and go read our newest review
      - l_e_e
        
        How does posting a new review change anything?
      - http://www.headfonia.com/ L.
        
        Dude. Really?! Jeez, I’m out.
      - l_e_e
        
        Exactly what I thought. Thanks for confirmation.
      - http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
        
        Way to go pissing off L.
        
        Gotta say that you’re crossing the line now. Your comments and attitude are no longer moving the O2 conversation forward. You’re clearly just trying to provoke a reaction as a last ditch effort to “win” this conversation. Very uncalled for.
        
        Everyone has an opinion and it should be respected, whether you agree or not. I’m all for a spirited debate, but let’s keep it focused on the topic.
      - lee_is_back
        
        I know, I’ve picked up on Brian Fu’s “style” of commenting. I’m not trying to win anything here, just replying with stupid comments to other stupid comments.
      - http://twitter.com/Brian_K3 Brian Fu
        
        I’m not sure what to feel because you need to pose as two different users to reply to my comments.
    - http://profile.yahoo.com/DGGOMJDU653O25X27H7HOHEBHE Ragno
      
      I must agree with Brian Here… I believe he does discredit other well established designers on a constant basis and I think that is pretty much just bollocks.
      - lee_again
        
        You’re free to think or believe in whatever you like but that doesn’t change NwAvGuy’s and other’s measurements or the performance of said designers’ creations.
- http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
  
  Yes, thank goodness all the O2 supporters are here to save us from ourselves.
  - http://www.facebook.com/people/Fred-Maxwell/1307740682 Fred Maxwell
    
    When subjectivist tripe results in sales of inferior products and lost sales of superior ones, it harms the entire industry. J. Gordon Holt, founder of Stereophile magazine summed it up this way in a 2007 interview:
    
    “Audio actually used to have a goal: perfect reproduction of the sound of real music performed in a real space. That was found difficult to achieve, and it was abandoned when most music lovers, who almost never heard anything except amplified music anyway, forgot what “the real thing” had sounded like. Today, “good” sound is whatever one likes.
    …
    Since the only measure of sound quality is that the listener likes it, that has pretty well put an end to audio advancement, because different people rarely agree about sound quality. Abandoning the acoustical-instrument standard, and the mindless acceptance of voodoo science, were not parts of my original vision.
    …
    Audio as a hobby is dying, largely by its own hand. As far as the real world is concerned, high-end audio lost its credibility during the 1980s, when it flatly refused to submit to the kind of basic honesty controls (double-blind testing, for example) that had legitimized every other serious scientific endeavor since Pascal. [This refusal] is a source of endless derisive amusement among rational people and of perpetual embarrassment for me, because I am associated by so many people with the mess my disciples made of spreading my gospel. For the record: I never, ever claimed that measurements don’t matter. What I said (and very often, at that) was, they don’t always tell the whole story. Not quite the same thing.”
    - dalethorn
      
      What’s amusing about this is that Holt very vociferously opposed testers at Stereo Review and other respected publications because they refused to value listening above measurements. I subscribed to Stereophile starting in 1973.
  - Cola Bear
    
    No one can save you from yourself but you. All that has been done, in essence, is to shed some light in the hobbyist headphone arena. Not his (NwAvGuy) fault that so many seemingly good products are either dangerous to use (non UL/CE compliant), dangerous to headphones (Asgard) or don’t meet the manufacturers stated specifications (NuForce & AMB). Those are all the responsibilities of the manufacturer. Why as a consumer who works hard for your money would you buy subpar goods?
    
    There are other good products out there. No one ever said the O2 was the end-all be-all. It was designed to be audibly transparent with low part count, not very expensive and DIY friendly with no critical tolerance parts. It has met all those points and then some. An amp is either transparent or it isn’t and the O2 meets all the requirements for audible transparency.
    
    Other amps may look nicer, be gold plated, have 10mm thick front plates, a Blue Velvet pot, huge knob but cannot be more transparent than transparent.
    
    That I can either build an O2 for around $50 or buy one for $150 is a tremendous value.
http://www.facebook.com/people/Hari-Susetyo/1211480515 Hari Susetyo

I often come to this website just to find out how the character of an amp or headphones … before I buy or try it..

because I have been following Mike review in headfonia until now.. I quite know how is the sound that he prefered.. what he likes or what’s not

so if there is a new stuff that they reviewed here, I immediately understood how is the sound of the new things compared to the stuff that they have tried before (and among those things there must be one-or-two that I’ve tried it too) so it’s so much easier to get the sound-image of the new things even before I try it myself.

that alone is enough to make me a reader of headfonia….
- http://www.headfonia.com/ L.
  
  Thanks Hari!
- http://www.facebook.com/donunus Don Vittorio Sierra
  
  I also follow your style of reading reviews. Its the relative comparison of things and knowing what the reviewer likes that can make one learn about what something sounds like without having to hear it for ones self.
http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer

You know one of the big deal breakers with the O2 is that it’s really not friendly to live with at all.

It’s designer advertises it as a “portable amp”, but it’s far too big to put in your pocket. So count on always needing a bag with you. You will also need to stock up on 9V batteries as you’ll only get 8 hrs out of each set of batteries. Ouch, that gets expensive. Sure you can use rechargeable batteries, but the O2 doesn’t have smart charging so you need to baby sit it every time you recharge it so you don’t fry the batteries or the O2. Oh, and don’t forget that there’s no low battery light either, so it could go dead at any minute. You could skip the batteries altogether and use a wall wart charger, but then there’s yet another thing you need to drag along.

It really needs to have a lithium battery with a reasonable battery life, USB charging, and much smaller packaging.
- Andrew Schroeder
  
  or you know, get two sets of batteries and a wall charger.
  - http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
    
    True, but the O2 is clunky enough to lug around. Now you’ve added extra batteries, a charger, and have increased cost. Plus, you’re stuck doing the battery shuffle, which gets old quick.
    
    Once you’ve had a true slim line amp with the convenience of USB charging, you’ll never go back.
http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer

Relevance?
- Ely Maranhao Filho
  
  Have you read the links?
  - http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
    
    Yes, but I’d rather hear what you have to say first hand.
    - Ely Maranhao Filho
      
      Recently I’ve decided to listen music seriously again. I’ve read a lot stuff, and in the last months I acquired a senn hd650, an ath-m50, a fiio e9+e17, an audinst amp-hp and a burson ha160ds.
      The diference between the headphones are obvious, but the diferences between the headphone amps, I simply don´t know… Sometimes I think the burson is better, but maybe I don´t want to admit that my money wasn´t spent wisely.
      I´ll ask some friends to make a blind test, but it will take some time.
http://www.facebook.com/larryganz1 Larry Ganz

You have to call it like you see it, or should I say, “hear it”. I applaud you for telling it like it is. We all hear differently due to different ear shapes and middle/inner ear health/age, and our brains interpret what we hear differently. And then there are personal preferences, some like things spicy and some like things sweet.

True, measurements are nice, but they need to be only a part of the equation. We can’t say that all amps that measure good sound good, and we can’t say that all amps that measure poorly sound bad. The eXStatA electrostatic amp is reported to have some of the highest distortion levels in an audio amplifier, and yet while it sounds strained and grainy with the Stax SR-007 it can sound lovely with the Stax SR-009. The uDAC-2 can have high levels of distortion measured with recordings hitting -0 dbfs, but with well-done masterings the device outperforms most other gear in it’s price range.

And sometimes the electrical circuit will have a synergy with one set of headphones but not another. I don’t believe anyone can say that there is only one output impedance or dampening factor that works well with all headphones, and voltage swing or current output can greatly affect the sound as well. To have NwAvGuy imply in his blog that your review is biased, because you didn’t like it with certain phones like the hard to drive HD650, is to ignore synergy and to deny an understanding that what sounds good to one person may not to another.

In my case, I have only heard a couple of amps that drove the HD650 well enough to make me enjoy them, including the Balancing Act, Zana Deux, and Schitt Valhalla. I disliked them on my maxed Woo WA6, Dark Voice 336i, and EF1 amps – they sounded dull and lifeless and veiled when underpowered and I got rid of them. I’ve owned them twice, and came to the same conclusion. I always gravitated toward the HD600 instead, which are slightly less demanding on an amp and behave a little better with lesser amps.
- alejandro vidal
  
  No one has stated that “all amps that measure good sound good”. What we can say is that all amps that measure good (to be audibly transparent) will have higher fidelity that amps that measure poorly, and that all amps that measure good will have indistinguishable sound.
  - http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
    
    Well put.
    
    I’m not sure about the “indistinguishable sound” part though. Technically it’s a correct statement. But because different amps are made of different types of parts, sometimes sonic results are just a bit different. Maybe “virtually indistinguishable sound” is more proper.
    - alejandro vidal
      
      Indistinguishable in the sense that the sonic differences that you speak of are beyond the threshold of human perception. After this threshold 2 amps might have different parts, and even measure differently, but they will sound the same.
      - http://www.facebook.com/profile.php?id=100001174173334 Scott Boyer
        
        Not necessarily.
      - alejandro vidal
        
        How could 2 amps with sonic diferences beyond the threshold of human perception “not necessarily” sound the same?
- dalethorn
  
  “We all hear differently due to different ear shapes and middle/inner ear health/age, and our brains interpret what we hear differently. And then there are personal preferences, some like things spicy and some like things sweet”
  I’ve always believed in High Fidelity and never thought of it as a religion, although there certainly is a lot of black magic in the better designs. The “hear differently” thing makes sense when we speak of absolutes like “how does it sound?”. But it doesn’t make as much sense when we speak of comparisons like “which one sounds airier?” If person A thinks amp A sounds airier than amp B, and person B thinks the opposite, then I don’t attribute that to hearing – I think there are probably other factors that didn’t get accounted for in the test.
http://www.facebook.com/jeffreytang71 Jeffrey Tang

Well, I’m enjoying the O2 with my DT48A, at first I felt the Meier Arietta was on par, but it seems that the O2 is not as limited in the frequency range span. I have also tried them with my DT48S Nagra and you can only imagine what i hear. Very Hi End sound. Simply amazing….have been posting less and enjoying the music more since i got the O2.btw the Meier Arietta was preferred over many other amps for its neutral sound, other amps like the Burson and WA6SE had slight colorations. YMMV.
Deniz Yildirim

How do people think this compares to the Matrix M-Stage? Any help would be appreciated.
http://www.facebook.com/donunus Don Vittorio Sierra

I have a question. I don’t know if it has already been answered here but is there going to be a fixed version of the o2 where it could take higher input voltages than it can because the jdslabs O2 that I have in front of me clips with a lot of modern recordings at high gain even when the amp volume is not turned up very loud. I really love the sound of this amp even at high gain when playing non-remastered 80s cds for example using my beyerdynamic dt250-250 but once the albums are really mastered too hot, the amp starts to clip.

I can also tell that it is really an input problem because if i turn down the volume levels from within foobar and turn up the knob of the amp, the clipping goes away.
- dalethorn
  
  I’m finding that when the O2 drives something well on low gain then it sounds good. On high gain I seem to get a disproportionate amount of noise and distortion for the amount of gain I’m getting. For an amp that cost me $140 USD assembled (by JDS Labs), it’s a good deal I think.
  - http://www.facebook.com/donunus Don Vittorio Sierra
    
    I agree. I use low gain most of the time. The only time I need to switch to high gain is when the music playing is very quiet like in old cd masterings of the 80s for example. In that situation, the input clipping doesn’t happen anyways so its all good. I just want to say the O2 is a really nice amp!
http://www.facebook.com/cce121 Chow Chi Eng

came across this humorous analogy from my friends as I tried to give my 2 cents on forum regarding amps.

“Stop ‘educating’ people to look at audio gears in your ‘objective’ way,then conning beginners to look at those measurements every time they want to judge. That’s like saying a chicken cutlet is not tasty because the salt is not distributed evenly,this fat part has more salt than meat. So that it’s definitely not nice to eat.”
Andrew V. Uroskie

OMG LOL!! It’s like the Scientologists whenever the O2 is discussed! If you don’t praise us, YOU’RE WRONG. Not only that, you’re wrong and you’re stupid. And you also don’t know what you’re supposed to like, which is what we like, which is the O2. ABX, neutrality, wire-with-gain, eternal life, L Ron Hubbard… Bah ha ha!
- Andrew V. Uroskie
  
  And just like the Scientologists, watch a million followers descend on this forum to “defend the faith!”
Bootney Lee Farnsworth

I recognize that I’m a bit late to this party, but I’d nonetheless like to share my views.

I think some of the objections to this review simply stem from the mindset it betrayed. One may choose to rely on more than science when judging a product, but that doesn’t mean science can be altogether ignored.

For instance: If an amplifier is verified to be completely transparent, the phrase, “I found it lacking X-attribute and Y-attribute,” is no longer valid. Accuracy demands such statements be phrased more like, “I found it lacked the added X-attribute and added Y-attribute to which I’ve grown accustomed.” Otherwise, you’re really just saying that either the music or headphones, or both, lack those attributes.

In the case of headphones, that could very well be true. But for music? Never. Transparency means that only intentional sounds from the source recording are reproduced. All things being equal, if you find something lacking a particular attribute, you were supposed to find it lacking; it was intentional.

That’s not at all to say you have to like a transparent reproduction of music, but transparency and its implications should be acknowledged.

Put another way: you cannot blame a ruler if you don’t like the measurement.
- dalethorn
  
  In my mind the thing about evaluating the O2 is basically price -vs- performance, or where does it fit in the market and just how critically do we have to examine this 100-plus dollar amp? I don’t see a problem running a billion dollars worth of measuring gear on it and printing the results, but still, after getting those results, I don’t think it merits a lot more than 100 dollars worth of evaluation unless there’s something unusual in the features or sound. And if there is something unusual, it’s still 100 dollars. If I bought a car for $20k that had a feature that was previously only available in a Rolls, would it be reasonable to judge the $20k car or even that specific feature against the Rolls and its feature? A comparison would be good, but it shouldn’t have to be contentious when you’re only paying the lowball price.
  - Bootney Lee Farnsworth
    
    For the most part, I agree with you. Beyond comparing the O2, or anything else that’s targeting transparency, against other products with similar goals, I don’t even see the need for a review. I’d compare it to a well known transparent amp, and if it measured up, I’d call it transparent and then go on about my day.
    
    However, comparing it to a cMoyBB is inherently unfair, because they were designed with different goals. That’s why saying the O2 lacks the bass of the cMoyBB is nonsensical. Maybe it’s just down to semantics, but the more accurate statement is to say that the cMoyBB has more bass than the O2.
    
    Once any audio gear is established as transparent, it becomes the benchmark by which others are compared, not the other way around.
    - dalethorn
      
      Makes sense – thanks.
- http://twitter.com/Original_Ken Ken Stuart
  
  Bootney – you say ” For instance: If an amplifier is verified to be completely transparent, “.
  How is an amplifier verified to be completely transparent ?
  Do you hook it up to an Acme Transparency Detector Version 3 ?
  How do you know if the Acme Transparency Detector is working correctly ?
  Sorry, I rely more on science that you do, so I know that there is no such thing.
  - Bootney Lee Farnsworth
    
    I would think a man of science such as yourself should know that, although the Acme Transparency Detector obviously doesn’t exist, there are other instruments which do exist and can easily be used to measure a number of parameters associated with what people can and cannot hear. There’s no mystery.
    - http://twitter.com/Original_Ken Ken Stuart
      
      The only mystery is how you know that those parameters are associate with what people can and cannot hear ?
    - dalethorn
      
      You can quantify each, but how they sound all mixed together with the music will need a quantum computer to sort out. If the program can be written to do so.
      - http://twitter.com/Original_Ken Ken Stuart
        
        I think you are also missing the point – how would the computer know which measurement was audible and which was not ? Especially in combination with each other ?
        
        Of course, the answer is that the computer cannot know – it can only be programmed by human beings.
        
        And, if you had an island filled with the most brilliant computer programmers and electrical engineers, and every one was deaf, it would be impossible for them to create tests that determine whether an amplifier was transparent. Literally impossible.
        
        People keep putting the words “science” and “measurements” into their sentences to try and convince themselves that there is something scientific going on, when there is not.
        
        dalethorn
        
        So they would still need their hearing to confirm their measurements. But wouldn’t hearing bias their measurements? Is this saying that science is still beholden to philosophy?
  - alejandro vidal
    
    You can establish thresholds of audibility of the different “inaccuracy’s” (noise,distortion, FR and timing errors) of the signal and then compare them to the output of the amplifier. If the amplifier doesnt “add” anything to the sound then I don’t see why it could not be called “transparent”.
    - http://twitter.com/Original_Ken Ken Stuart
      
      How do you know that those are the inaccuracies of the signal ? How do you know that there are not interactions between those four quantities ? If noise is 4 and distortion is 10, it may be more audible than just noise at 4 or distortion at 10 separately. Or noise at 4 and distortion at 10 and timing at 0.11 vs noise at 6 and distortion at 3 and timing at 0.28. And so on. The idea that there are some tests that can establish transparency comes from the idea that “there must be tests that can establish transparency” and NOT from anyone with experience with audio and tests.
http://twitter.com/shigzeo shigzeo

I’m left with a ‘meh’ feeling after reading this review. But that’s fine. It’s happened before and will happen again. I come to Headfonia for the excellent photos, and always will.

At a recent Headfi meet, an O2 got plunked on top of my part of the table. It was a wonderful (and huge) surprise. At first, I thought it wasn’t a battery powered amp (certainly you can forgive me). It’s huge.

I tried it with Fostex TH900 and my trusty FitEar ToGo334. Yep, ‘black’ background. Noise noise at all anywhere. I used low gain with both at first, and with small volumes, high gain just to see, but I am NOT a listener of loud music. I kept low gain for both headphones.

I think this opinion has come out quite a few times in the comments to this review, but I’ll reiterate: the O2 disappears. I don’t mind amps that have sound, and indeed, have praised a few at TouchMyApps, but the O2 was an epiphany after rounding the table by some other amps, all of which cost at least twice. There were one or two other amps that almost disappeared, or maybe they did.

Meet conditions aren’t the greatest and we weren’t able to volume match.

Indeed, the O2 disappeared. I do agree with Mike that it would be better to have a 6,3mm jack, and maybe RCA inputs. Also, on the rear, the DC input would make it more wieldy.

But, come on, it’s a 50$ DIY amp. Or a 150$ amp all built. Incredible to say the least.
- http://www.headfonia.com Mike
  
  Thanks for sharing your impressions, shigzeo.
- Fabio_Rocks
  
  I am waiting for an o2 with 6,3 mm jack and rca on the back, there are different build of this amp. This one I take is a semi desktop.
Cola Bear

Hillarious! TY )
dalethorn

One more thing that has been left out of the comments, certainly by the so-called objective people, is illustrated so: A couple years ago in Ohio we were walking in the woods, in winter when there were no leaves, and my wife saw a deer. I said “Where?” She pointed straight ahead and I couldn’t see it. After about 2 minutes of pointing I finally figured it out. And it wasn’t all that subtle. If you knew what to look for it was right there, 30 feet away, plain as day. And so assuming you have high enough rez tracks to hear a difference, you still have to learn sometimes what to listen for.
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