Bakoon HPA-01

Disclaimer: This review is written by me, it reflects my thoughts & honest opinion about the product.

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Me:  I am an amateur musician & avid admirer of music. I would like to call myself a music enthusiast, rather than an audiophile. I was inspired by music since childhood, and as the time passed, the passion of music grew in me, and that subsequently led me to join Head-Fi. I usually like to listen to Indian Classical Music along with Bollywood songs. My main listening genres include classical, vocal, instrumental, jazz and sometimes pop.  With time, my sonic preferences have very much grown. I avidly admire transparency, accuracy along with neutrality, I mostly listen to full sized open back headphones and my favorite headphone is AKG K812, which I run from solid state amplifier. I prefer & admire transparent solid state headphone amplifiers simply because they provide best possible accuracy, transparency & reliability.
 
I will describe this review in simple words that is readable & understandable to anyone. Let’s have a look at this amp from the eyes of a music enthusiast, shall we?
 
Intro:  The name “Bakoon” originated from the words “Baku” and “Un”. “Baku” is a supernatural creature from a Japanese mythology that is associated with dreams, and ”Un” represents luck. Bakoon Products uses its proprietary technology called “SATRI” in all of it’s products. SATRI technology was initiated by Akira Nagai, in 1980’s Japan. Here is the incident: It was at one bookstore when Akira Nagai, who had been developing precision metrology instruments in Japan during 1980s. The book that he picked up contained debates between a philosopher and a musician on the topic of “Time” of music and “Kshana” (moment)
 
All images are high resolutions, click to enlarge & zoom in.
 

 
The concept of “How short of a time can a human sense?” did not leave Akira Nagai’s mind, as he was aware that this question also applies to audio circuits by means of excessive time distortion, reaction delay and time-related inaccuracy. After endless research, during a boat trip, Akira Nagai discovered the solution to his dilemma. Enlightened by this discovery, he developed a circuit that was revolutionary. The circuit then transitioned into the very first D/A converter and amplifier.
 
Bakoon had earlier released the HPA-21 (2995$), which had received good response overall, & now Bakoon has tried to bring maximum possible sound quality from HPA-21 at a lower cost, thus forming the HPA-01 amplifier, on the same platform as that of the HPA-21 by cutting down on un-necessary features.
 
Technical specifications of HPA-01:
 
 
 
Packaging & Accessories: The HPA-01 comes packed in a strong cardboard box with foam protection inside. Accessories provided are very basic & not complimenting the premium product. But that is a no brainer, since we are here for the product which happens to be very good.
 
Included Accessory:  A worldwide compatible charger with output of 16.8V along with an AC power cord to attach to mains supply.
 

 

 

 

 
Design, Build & Function: As expected, the HPA-01 has a robust build quality. It has a precise & accurate finishing. The case is powder coated in matt black. Feels well put together.
The circuitry & internals of the HPA-01 speak for themselves. Components are well laid out; most components are Surface Mount Devices (SMD) Components are placed in a symmetrical & neat fashion.  All components used are carefully selected. Board is excellently soldered and has a reliable workmanship. Architecture wise,  on the front side we have Volume control knob, two headphone jacks present in 6.5mm format along with gain & power switches. On the rear side, we have Power socket & switch, Volume control is feels silky smooth to turn. Headphone socket is clip type. To remove the case & access the circuitry, one has to remove top four screws using allen keys Size (2mm) the top cover will come off. 
 

 

 

 

 
The HPA-01 has two headphone jack outputs: One is current mode (newer technology) & the other one is voltage mode (which is found on almost all of the headphone amplifiers on the market today). So what is this current mode amplifier? Simply put, it is an amplifier which uses current feedback in its circuit to function. However that’s merely generalization. In reality it’s much more complicated. But whatever the theory, in practice, the sound quality of voltage mode is on par with current mode. It is not that current mode necessarily sounds always better than voltage mode, it is a “give and take” situation. & a huge price difference of current mode amps over voltage mode amps cannot be justified.
 
The HPA-01 runs purely on battery power. It has 2* 8.4V batteries inside the case, with each battery supporting to one channel. In my case, battery power lasted till about 5 hours under my usage. It has a dedicated battery charger provided in the box. When charging, red light is shown on the charger & green light is shown when charging is complete. Re-charging took me about 7 hours or so to attain full charge capacity. If the charger is connected while HPA-01 is operating, the charger gets dis-engaged by a relay mechanism. The battery power helps us to avoid heavy power cables or expensive power filters. It is very helpful if one is constantly on the move or electricity is unreliable, like my case in India. It also helps in achieving lower noise, & supply pure power to the circuitry. Initially, the headphone output sockets are very tight & cause deep scratches on headphone cable 6.5mm jack. It requires some time to loosen up, & then it’s good to go. Overall, excellent build in every area, Practical design & Great quality.
 

 

 

 
Sound:  The HPA-01 is a modern machine with the aim to amplify & deliver exactly what is fed to it; If sonic chain is perfect, it puts out a impressive sound quality, transparency & soundstage. It does not have any particular coloration of its own. Soundstage depth in HPA-01 is amazing It has a fully circular 3D imaging. Detail retrieval, and dynamics are excellent. Overall the sonic presentation contains high level of transparency and accuracy.  Absolutely zero audible hiss/noise, and zero EMI pickup. Another plus point here is, the device has relay mechanism which prevent any noise pop’s when headphones are plugged in/out. This way, a better safety is guaranteed for the precious headphones.
 
Current mode provides superior, better control to the headphone driver, lower distortions, but a catch: slightly reduced soundstage width. Whereas the depth is amazing. Sounds slightly smooth with deep bass, slightly intimate mids, with.higher frequencies very being consistent & smooth.
 
Voltage mode:  Bass is accurate but lacks the depth of current mode. Mids sound far out, thus making impression of “expansive soundstage” The highs have a few rough edges. But due to very high gain, this mode has audible distortions & thus disappoints. Overall, the HPA-01 is a smooth & slightly laid-back/relaxed sounding amplifier. It is quite clear that, HPA-01 audibly does not match well with wide range of headphones. By my observations, HPA-01 suited well with sterile/analytical headphones like AKG K702 & HD800. I would not quite like the match with LCD-2 or K812, these happen to be slightly musical/smooth sounding headphones.
 

 
Driving Power: Contrary to popular amp's, the output impedance of the HPA-01 (current mode) happens to be very high & thus all headphones cannot match well from this machine. Nevertheless ,the HPA-01 is very powerful when it comes to driving. It can drive any dynamic headphone in its default gain. Infact, I couldn’t flip up the gain switch, because the HPA-01  is so powerful, low  gain is more than enough to drive vast majority of headphones. HD800 & AKG K702 pair very well with the HPA-01.  It can also drive planar magnetic headphones with ease.The HPA-01 is very sensitive &demanding at the input port. Meaning, it is very sensitive/picky about what source or DAC you feed it into. Feed a very high quality DAC & enjoy the blissful sound quality. Otherwise you are all in for a muddy sound. I kept trying to pair the HPA-01 with many DAC’s, but not at all happy about the final sound quality, that is until I connected my trusty DA8. Then the HPA-01 really began breathing life into music. 
 

 

 
 
Comparison:  Considering its design, the HPA-01 has no competition. But price wise, around 2000$ we have a few well respected veteran amplifier devices, which are albeit desktop AC powered machines namely, Yulong DA8, Questyle CMA800 (with very similar current mode technology), Benchmark DAC2, Sennheiser HDVD800. If we compare the HPA-01 with the above devices, it is apparent that the HPA-01 obviously has lesser features & performance to offer. Let’s admit the truth. All these devices outperform & defeat the HPA-01 in terms of sound quality & features.The battle is over before it began.
 

 
As a comparison, I will be comparing The HPA-01 with Objective2 amplifier. You might ask me, why am I comparing a 130$ amp with a 1700$ one? Because,
Ø   - Both of these are designed to be portable/ transportable & are battery powered.
Ø   - These machines are pure standalone amps, with high performance circuitry inside them.
Ø   - Designed & Aimed to provide purest of the sound quality
Ø   - Both of these are very unique amps with importance of their own.
 
We all probably know that O2 is absolutely transparent, highly cost effective & provides an exceptional performance. But it is limited by its price. Imagine an O2 amp, with significantly improved sound quality. But with a slight flavour of smoothness & darkness in the sound. That would form the HPA-01. But the HPA costs 13 times more, hence having less than desirable competence.
 
Verdict:  The HPA-01 achieves what it is designed for; for that I will call it “the achiever” It is unique in its own way. There are very less battery powered amps available with benchmark sound quality. HPA-01 is one of them. It is a very functional, & unique amplifier which delivers what is fed into it. It does its job well, very well. But it's performance is easily challenged by devices costing way under the price of HPA-01. Therefore, I can recommend HPA-01 only to those who would like battery powered headphone amplifiers. For the rest of us, there are much better performing devices at the asking price, Hence I would not recommend it. Thus I rate it 2.5 out of 5 stars.
 

 
Like every product, the HPA-01 too has drawbacks. I will list them:
 
Ø   - HPA-01 lacks value for money aspect. At 1700$ there are plenty of high end amps with better features & better performance with respect to sound quality.
 
Ø   - Very sensitive to Input port. Now this can be also advantage, assuming you have high performance DAC. The HPA-01 detects even slightest change in DAC behaviour.
 
Ø   - HPA-01 leaks sound even if volume knob is zero. Channel imbalances seen in initial stages of volume control.
 
Ø   - Gain switch applies only to current output. The gain of Voltage output is too high, can’t turn volume knob above 10% of the capacity.
 
Ø   - The headphone output socket clips are very tight, & cause scratches on headphone’s jack.

 
I purchased a Bakoon HPA-01 off Massdrop for around $1200 (it is normally around $1700 retail) due to the reputation of Bakoon Japan for making stunning amps. The HPA-01 is from Bakoon Korea, utilising the same technology as the Japanese models. 
 
I had just purchased a Hugo and was looking for a compact amp to have on my desktop to pair with it, especially one good with planar headphones. The Bakoon technology is unique in a number of ways. First, it uses battery power, charging automatically when switched off. It also has two headphone outputs: One "current" output, and one regular "voltage" output. The former, instead of the usual low output impedance, has a very high output impedance instead, which works well with current-hungry headphones. However, the headphones used have to have a completely flat impedance, otherwise there will be significant shifts in the frequency response. 
 
This lends the amp to working well with planar headphones from Audeze, Hifiman and MrSpeakers, but not with your regular fare of headphones from Sennheiser, Beyerdynamic and AKG for example. Those headphones have to be used with the regular "voltage" headphone output. 
 
Unfortunately I was quite disappointed with the amp considering what its retail price is. While it did a very admirable job driving all my headphones, compared to the headphone output of the Hugo, there was distinctly less resolution using either socket, even after I had left the amp running for some days (in case this had anything to do with the components needing some run-in). Not helping this was measurements showing significantly greater distortion from the voltage output, especially disappointing given that the amp uses battery power to reduce distortion from the power source. 
 
I guess part of the problem is the timing of this amp -- DAC/amps have been improving so much that it is hard to be competitive with a dedicated unit, especially one that is clearly being sold with a huge dealer/distributor markup when there are a number of great companies now making fantastic amps that sell direct.
 
Sadly not recommended.