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JDS Labs Assembled Objective2 Headphone Amplifier Reviews


A High Performer for a Low Cost, but Don't Mind the Front-Panel!


Pros: Excellent sound quality, great price/performance ratio, battery and/or AC powered, adjustable gain options, no background hiss, packs plenty of power

Cons: Everything is on the front-panel, low-volume channel imbalance, too bulky to be used as a portable amp, finicky with TRRS jacks

    Without referring to "He-Who-Must-Not-Be-Named's" (A.K.A. NwAvGuy) blog, and speaking from my own listening experiences, I really do think the Objective 2 is a great headphone amplifier. No, I don't think this is the amp to end all amps, but it's a dang good one and it only cost me $156 USD (which includes the Triad brand WAU12-200 AC adaptor). In fact, it can be found even cheaper nowadays from the same vendor, JDS Labs, for $140 (including the same adaptor).         What's in the Package? JDS Labs Objective 2 headphone amplifier, wrapped in an anti-static bag 2 removable, rechargeable Tenergy 9 V nickel-metal hydride (Ni-MH)...
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YoYo JoKeR

Objective2 : Wire with Gain


Pros: Sound Quality, Build Quality, Customization, Value

Cons: Portability Issues

The Objective2 is my first amp along with my beloved HD600 headphones. Here is my review after my experience with it for several months.     Intro : I am an 21 year old Engineering student living in a small town in India. There is not much audiophile-community presence in India, Though lot of potential remains to be tapped. Auditioning an amplifier before purchase is almost impossible in India.   I would like to call myself an music enthusiast, rather than an audiophile. I mostly listen to Bollywood and Indian Classical Music.   I had bought off the O2 amp solely based upon its reputation, and also because of not being left with enough funds buy an more...
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In the amp jungle this little Tarzan holds its own


Pros: value, clarity, small footprint, runs cool, reliable, can drive many headphones

Cons: see review

You know that feeling when you wake up in the morning and you can smell the coffee (Columbian), bagels (plain) being toasted and birds singing (bunch of them). It's the feeling of life just being right. That's how I feel today so I thought let's write a long overdue review of this little wonder called Objective2 headphone amp. There are many reviews with detailed numbers and measurements but my review is just my opinion based on many hours of listening all type of music.   My unit was purchased used for only $55 shipped here at head-fi few months ago. This is my second O2 amp first one was a JDS my current one is Massdrop made in China. Don't let the price tag fool you this little...
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Excellent in Price Category and Value


Pros: Light, Gain Switch, Replaceable Battery

Cons: Not Lithium Batteries for More Power or Run Time

I've been reading so many replies and reviews how the O2, Magni and Vali sound the same. After weeks of listening to all of them, (yes I have them all) they are all not exactly the same . I've been using the same music and all else in the system is the same and have only changed the amps. Started with O2, then went to Magni. Yes the Magni and O2 sound very close. The Magni does sound a tad processed and thin compared to O2 but the Magni does have more authority as it is more powerful in comparison even though they all seem to struggle reproducing the source. The O2 is a really nice amp but when compared to the Magni the O2 is better overall, but sound wise when compared to Vali in sound...
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Pros: Noticeable improvement in some cases, very little improvement in other cases

Cons: Everything is on front panel

UPDATE: So, this amp makes the signal just a bit cleaner. It was pretty noticeable on my Q701s, noticeable for general clarity, separation, esp cymbals got a bit clearer. For my HD 558 (w/ foam mod), slightly noticeable, but not that much. For my closed-back headphones->very minuscule, you might notice if you listen really hard. When I bought this, I just needed power for my Q701s so I was surprised the quality actually improved, thus I might have exaggerated my initial impressions a tiny bit. Overall the difference minor even for the Q701, but still pretty noticeable. It's not OH WOW I CAN'T BELIEVE THIS, IT'S LIKE DAY AND NIGHT kind of difference.   I bought this amp for my...
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The Little Beast that Laughs at Everyone


Pros: Does its Job and Does it Well

Cons: Pricey? Even for what you get . . .

Lets see, a battery powered Amp that runs for hours on hours with a charge, or a desktop Amp that can throw almost a watt out and run forever?   I don't know - its sort of both. It is too big to be taken anywhere, but definitely small enough to travel if you want it to. I ordered mine with a black face plate which I think is a little cooler looking.   There appears to be some "mythology" surrounding this amp, some claim it "ruins" their sound quality while others think its awesome. I think its an amp - that is, it takes a signal, amplifies it, and otherwise has no real impact on what you hear. It has no real noise I can detect (except at max gain of 6.5X with nothing playing...
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It enhances the audio overall, and the performance is affected by the source the most.


Pros: Good sound to price ratio, Very versatile for modding.

Cons: short battery life (8-9 hours), long charge time (12 hrs using 18V ac, 770mA), audio quality becomes source dependent. Not very portable.

This is my first review submission for head-fi, hope that it could provide some comparison and enough information to let you decide whether to make a buy for it. But do remember this review is from my point of view and the ultimate decision is down to your ears to decide. First few things to start off with here that i believe will be important: The sound of O2 depends greatly on the source. [[SPOILER]]  Comparing O2 with other amplifiers: [[SPOILER]]  Stock O2 sound signature: [[SPOILER]]  Pros: [[SPOILER]]  Cons: [[SPOILER]]  Interesting things to share about O2:  [[SPOILER]] I hope the above review can help! Please do PM me for questions regarding op amp rolling for the O2.

It might not deliver more power than your laptop or phone jack


Pros: Very accurately reproduces the source signal; I guess it could help if the source's headphone jack isn't strong enough

Cons: Could use more power

The objective facts   Background: I listen to music on a higher-end (purchased for $800) Asus laptop, or my Galaxy Note 2 smartphone. With my SRH940s, the phone sounds better in terms of sound signature, but with my Sennheiser HD800s, the laptop sounds better for some reason. But they're both very close. All of these experiments were done listening to music on Spotify 320kbps; that's how I listen to headphones 99% of the time so that's the only way to test for my purposes.   How I tested this: I connected the O2 amp, with low gain, to my laptop's output jack. I set the volume of the O2 amp to its highest level (in other words, I controlled the volume of the music from my...
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Excellent piece of kit (UK made model)


Pros: Size, performance, facilities(custom model)

Cons: None

I bought this to listen to my vinyl on my Hifiman HE-400 phones.  It does a great job of driving them with a very neutral and I can hear detail that my £5500 worth of amp and speakers don't pick up.  The JDS Labs would cost $191 shipped to the UK.  I bought a really nice version from a UK based eBay supplier (macwidow2011) - Swiss made board, neutrik connections, ALPS pot, RCA inputs and outputs with 1/4" jack - all for £109 shipped. 

A DIYer's Dream Build (or you can just order an assembled one)


Pros: Ability to build yourself, modification options, case engraving, customer support

Cons: Would love for the LED to indicate low battery/charging

You've already heard that the sound quality of this amp does not match its (low) asking price. You already know that it's one of the best SS desktop headphone amps you can get for your cans at any price point, really. So why am I writing another review on an amp that you KNOW is going to be awesome? Well, my review is for those who like to build their own amps and JDS labs is a company that "gets" the DIY movement and have made NwAvGuy's design really easy to build for those of us who like to roll our own gear. My review is meant for those who might be interested in ordering a DIY kit but who might not be sure of what they're going to get:   Remember back in the day with the O2 was...
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