Objective 2 Headphone Amplifier Review

Standard Objective 2 Headphone Amp

The Objective 2 headphone amplifier (commonly referred to as the O2) is an inexpensive, quality amp designed to combine performance and versatility in a small, inexpensive package.  The Objective 2, originally designed and built by the anonymous electrical engineer only known by his online blogger handle, "NwAvGuy" or Northwest Audio and Video Guy, aims to upset the audio snobbery associated with headphone amp products that often perform poorly for their respective price point.  NwAvGuy wanted to prove that a quality, solid-state headphone amp can be built for a very low price, while simultaneously delivering good performance.  When you compare the performance of the O2 to other solid state amps from other companies, many of which cost several times more, it's clear that the Objective 2 is one of the best, if not the best, budget, audiophile-grade headphone amplifier on the market.

The Objective 2 was a reference design, engineered and constructed by NwAvGuy and is essentially an "open-source" product.  NwAvGuy makes absolutely no profit from the Objective 2 and is not involved in any way with O2 sales, as he states on his blog.  The O2 is built and sold from several retailers. Despite different brand names, the Objective 2 is essentially the same (there will be very minor aesthetic and price differences).  The O2 is also available in several different flavors.  I received my DIY kit from Mayflower electronics, as of this writing the kit costs $95 dollars.  It includes all of the necessary components to build a standalone Objective 2 yourself.  Another DIY alternative is to purchase the O2 board, and source the electrical components yourself.  This method is cheaper, but obviously requires more effort.  Other flavors include the already built standalone Objective 2, the Objective + ODAC combo (the amp combined with NwAvGuy's DAC board) and purely desktop versions of the Objective 2 with a 6.3mm port as opposed to a 3.5mm port.  As previously mentioned, I purchased the DIY kit, which is essentially the standard $120 dollar Objective 2.  This is the model being reviewed.

The Objective 2 is housed inside an aesthetically pleasing, well built aluminum housing with a brushed aluminum front plate.  It is relatively minimalistic in design, with the O2 being a performance oriented product, it's not designed to be an eye catcher.  All things considered, it still looks very nice, and there is a kind of simplistic beauty to such a low cost device.  The standard O2 has all front mounted ports.  There is a 3.5mm input, 3.5mm output, power input, power switch, volume knob, power LED and a gain switch (which can be configured to either 2.5x or 6.5x gain).  One unfortunate downfall of the Objective 2, is that all the ports (even power) are located on the front of the device.  However, given the price and the reference design, it is an acceptable compromise.  Furthermore, modified versions of Objective 2's can be purchased with rear power from Mayflower electronics (although it will cost you extra) and the Objective 2 + ODAC combo has a rear mounted USB port, so that your don't have to run your 3.5mm line-in to the front like with the standard O2.  The Objective 2 is a pseudo portable device.  I consider it to be too large and unwieldy to technically consider it a portable headphone amp.  However, portability can be achieved, courtesy of the dual 9-volt, rechargeable batteries housed inside which allows listening on the go.  These batteries allow seven to nine hours of play time before running dry.  The batteries charge every time the O2 is connected to power.

The Objective 2 is designed and built to exacting specifications, and every single technical aspect is available for review, unlike other amplifier brands who selectively hide specifications.  I suggest heading over to NwAvGuy's blog to check out the technical specifications as they are extremely in depth.  I will only scratch the surface of the O2's technical specifications only to illustrate the quality of the amplifier.

The problem with many other headphones amplifiers is high output impedance.  Many comparable and even more expensive headphone amplifiers have an output impedance of 10-Ohms or more.  According to NwAvGuy's blog, high output impedance essentially muddies clarity and dampens bass response.  Having side-by-sided the Objective 2 with standard outputs, such as audio outputs from laptops/ portable devices as well as other amplifiers, I agree with NwAvGuy's assessment.  The Objective 2's low, 2-Ohm output impedance resolves this problem.  The Objective 2 produces an extremely transparent and crisp sound signature, courtesy of it's low output impedance.  Unlike tube amplifiers and other solid state amps, the O2 is extremely flat, there is little to no sound coloration, hence the name "Objective."  The O2 outputs slightly over 600mW of power.  This is enough juice to power any dynamic headphone on the market with ease.  The specifications state that the O2 can power headphones anywhere from a 16-Ohm to 600-Ohm impedance.  In other words, the Objective 2 has no problem being used with a wide range of headphones, from sensitive IEM's to full sized 300-Ohm + dynamic and even orthodynamic headphones.  The only headphones they cannot effectively power are electrostatic headphones.  In addition, absolutely no audio hiss or static is present, something I have noticed with other amplifiers.  Even with extremely sensitive IEM's, the sound is extremely crisp with absolutely no audible hiss present.

I use the O2 with particularly middle of the road headphones such as Sennheiser HD 280 Pro's, Grado SR-80i's, Etymonic  HF5 IEM's, Audio- Technica ATH-M50X's, Sony MDR-7506's etc.  None of these headphones technically need amplification from a power requirement standpoint, all hover between the 32-Ohm to 64-Ohm impedance range.  However, I detect a noticeable increase in bass impact and overall clarity when using my headphones with the Objective 2.  I also use the Objective 2 as a benchmark amplifier when I review headphones, as it brings out the accurate and unaltered sound signature of the headphones that I test and review as a result of it's lack of sound coloration.  The Objective 2 is a neccessity for my headphone reviews, and is my overall daily driver for a desktop headphone amp.  No matter what amplifiers I purchase or receive in the future, the Objective 2 will always be a part of my review process, due to its precision and sound reproduction accuracy.

The Objective 2 is hands down one of the best budget amplifiers you can buy.  Despite it's low cost, the O2 outperforms comparable and even far more expensive amplifiers.  It's a simplistic, minimalist design from a electronic and aesthetic standpoint.  For audio enthusiasts who demand a quality, accurate headphone amplifier for a low cost, should seriously consider the Objective 2 and Objective 2 + ODAC combo.

CLICK HERE for Mayflower Electronics product page
CLICK HERE for NwAvGuy's blog