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Headphone amplifier

Price (in Poland): 6490 zł

Manufacturer: Kyodo Denshi Engineering Co., Ltd.

Ikebe-cho 4900-1 Tsuzuki-ku Yokohama-shi
Kanagawa 224-0053 | Japan
tel.: 81-45-934-5234 | fax: 81-45-934-7576


Manufacturer's website:

Country of origin: Japan

Text: Wojciech Pacuła | Photos: Wojciech Pacuła

Published: 4. June 2013, No. 109

Japanese manufacturers can be pretty air tight (and I don't mean THE brand). Just have a look at the most important Japanese audio Magazine, issued quarterly „Stereo Sound”, and you will find a lot of reviews and advertisements of brands that nobody outside Japan ever even heard of. Examples? OK, here we go: Tech DAS (although a recent „Stereophile” review makes it less good of an example),Technical Brain (it looks like „The Absolut Sound” is trying to change that), Kripton Japan, Fundamental, U-Bros and many others. The fact is that Japanese manufacturers focus their attention and efforts on their internal market. Obviously there are also giant and well known corporations and brands like Sony, Panasonic, D&M Holding (Denon, Marantz), Yamaha, Onkyo, TEAC (Esoteric, Tascam). But these focus on mass-produced electronics and not on high-end audio equipment. There is also a third category – companies that decided at some point to expand their activities and to sell their products abroad. These are mostly quite small companies, often employing less than ten people. These are brands like: Accuphase, Luxman, Kondo, C.E.C., Furukawa, Oyaide, Leben, SPEC, My Sonic, Miyajima Labs. I think it is fair to include to this group also Phasemation, a brand owned by Kyodo Denshi Engineering Co., Ltd..
There is one problem with this brand awareness/recognition – only two years ago it was called differently – Phase-Tech, and many audiophiles would probably recognize that name. But when the company decided to enter European market they had to face a fact, that this name was already registered here, so they had to pick another one and came up with Phasemation. The core activity of this company is manufacturing cartridges and phonostages. Couple of years ago two more items were added to the offer – a D/A converter with digital K2 filter, and a proprietary master clock. Recently Phase-Tech presented also preamplifiers and power amps. Exclusively for Japanese market company offers also a CD Transport and integrated amplifiers. For our test we have received the newest addition to company's portfolio – a headphone amplifier EPA-007.
It's a small, aluminum box that holds fully balanced circuit, with two headphone outputs, that you can use for two pairs of cans with classic big jacks (6,3 mm), or one pair of balanced cans with double plugs. Unlike many other amplifiers this is not a simple design as it gives its user some room for adjustment for particular loading, and some tonal control, although not a classic one.


Recordings used during this test (a selection)

  • Bottleneck John, All Around Man, Opus3, CD 23001, SACD/CD (2013); review HERE.
  • Claudio Monteverdi, L’Orfeo, Ensemble La Venexiana, dyr. Claudio Cavina, Glossa, GCD 920913, 2 x CD (2007).
  • Depeche Mode, Heaven, Columbia, 47537, SP CD (2013); review HERE.
  • Depeche Mode, Delta Machine, Columbia/Sony Music Japan, SICP 3783-4, 2 x CD (2013).
  • Diary of Dreams, The Anatomy of Silence, Accession Records, A 132, CD (2012).
  • Ella Fitzgerald & Louis Armstrong, Ella and Louis, Verve/Lasting Impression Music, LIM UHD 045, UltraHD CD (2010).
  • Jim Hall Trio, Blues On The Rocks, Gambit Records, 69207, CD (2005).
  • Martin L. Gore, Counterfeit2, Mute Records, CDSTUMM214/247725, Copy Controlled Disc (2003).
  • Michael Jackson, Thriller. 25th Anniversary Edition, Epic/Sony Music Japan, EICP-963-4, CD+DVD (1982/2008).
  • Michael Rother, Fernwärme, Random Records/Belle, 091546, SHM-CD (1982/2009).
  • Miles Davis, Seven Steps To Heaven, Columbia/Sony Music/Analogue Productions, CAPJ-8851, SACD/CD (1963/2010).
  • Pat Metheny Group, Offramp, ECM, ECM1216, CD (1982/1999).
  • Pat Metheny Group, Offramp, ECM/Universal Music K.K., UCCU-9543, “Jazz The Best No. 43”, gold-CD (1982/2004).
  • Pat Metheny Group, Offramp, ECM/Universal Music K.K., UCCE-9144, SHM-CD (1982/2008).
Japanese versions of CDs and SACDs available on

We all know a simple rule that tells us that we should find proper speakers that would fit nicely to our amplifier and our room, right? It is simply about finding three elements that could fit nicely together and offer something more than just a simple sum of their features – a coherent, high-quality performance. In theory every well designed speaker should fit nicely with well designed amplifier, but experience proves this theory wrong on many occasions. Sometimes even a high-powered amplifier, with a very good power supply that allows it to deal even with significant impedance dips, and a great damping factor is not enough. It's not about specifications, it's about a good fit. Sometimes you need a low power amp with low damping factor and high output impedance to drive particular speakers properly. You're doubtful? Have a look at an email I received from Srajan Ebaen that was about just that.

Hello Wojtek!

Tell me, have you really listened to this particular setup [actually he asked about Devialet D-Premier AIR with Acuhorn Superleggera Giovane85 - WP], or your recommendation was based only on assumption basing on your experience with Devialet two months prior to Accuhorn test?
The reason I ask is because usually ultra-light drivers, like the one used in these speakers, hate to work with amps with high damping factor. Actually in such a setup bass rolls off much earlier than with tube amps that have high output impedance. You have noticed that yourself when you tried these speakers with Soulution amp. If you wrote that basing on actual experience I would have to reconsider the whole thing, but if you were just guessing … Well, than you made a huge mistake recommending this setup :-)
It so happens that this particular problem was a reason for designing FirstWatt F1 amplifier, which is a current source and not a voltage source amplifier. It sports a high output impedance (around 50 Ω), which makes it incompatible with most loudspeakers except for these with widerange drivers as these feature quite high damping themselves. When you hook them up with such an amp as F1 you can expect more bass extension and less restricted, more open sound. Knowing that Devialet has a very low output impedance I can't see how this particular setup could really work.

Srajan Ebaen

First thing first: yes, I listened to this setup and actually in a „flat” mode there wasn't enough bass. But Devialet is not a 'regular' amp, it has a tone control so I just added some bass and voilà! But the real point of Srajan's email was: not everything in audio is as it appears to be, so finding a proper match of amplifier and speakers in a particular room simple isn't easy.

By contrast headphones seem to be a perfect load. They usually have a high or very high impedance, there is (almost) always a single driver, which means avoiding any troubles with crossover as they don't need any. Usually their sensitivity is relatively high and 1W is all they need to sing. Oh, and one more thing – you don't have to worry about room acoustics. So, piece of cake, one might think. But only until one listens to some high quality headphone amplifiers with different pairs of cans. And suddenly one will realize that different coils used for different drivers, different loadings of particular diaphragms – all that makes it impossible to predict how particular pair of cans would fit with particular amp. And I know only two devices that clearly show the true character of each pair of can while hiding their own character pretty well. But even these two aren't perfectly 'transparent'. These two are: Leben CS-300 XS [Custom Version] and SPL Phonitor 2730. The former is a tube device, the latter is a solid-state. Both have a high voltage applied to amplification elements in common. EPA-007, the Phasemation headphone amplifier, is a third device I know that should offer high performance with any given pair of cans. Of course some setups will be better, and some bit worse, but they will always offer a similar tonal balance, that depends mostly on headphones, and a very good frequency response extension.

I had a chance to listen to 8 different pairs of headphones with Japanese amplifier, and the best results – no surprise here – I achieved with two reference pairs of cans: Sennheiser HD800 and HiFiMAN HE-6, meaning two models that worked fine with very few amplifiers so far. Let's start with the latter. This is a top planar magnetic model of this American company. They are a true challenge for an amplifier as they feature low impedance and quite low sensitivity too. Even when provided with high power they often deliver a high pitched, aggressive sound. But not with Phasemation. With this amp HE-6 delivered very transparent sound, with great resolution – which was exactly how planar magnetic cans should have sounded – but also a very rich and consistent one. There was a solid body, and good 3D imaging. Using this setup I listened for the first time to the newest Depeche Mode album, Japanese edition, which allowed me to call off my dark vision of this album, that I delivered when reviewing the first single Heaven (see HERE). Music on DM's album is made mostly by analogue synthesizers and guitars. That translates to particular richness and depth of the sound, and exceptionally wide frequency range of this recording. The Japanese amplifier delivered it all without even smallest issue, allowing also a deep insight into recording. This confirmed, for example, that the Heaven piece was strongly compressed.

The key feature of the sound of this device is transparency. While using Sennheiser HD800, and comparing directly to Leben, the latter seemed a bit dull. It's not true, or not entirely true, but it made me wonder. The solid-state EPA-007 delivered treble with better resolution, so after changing a tube CS-300 XS to Phasemation, for some time I was under impression that there was some emphasis in the latter's treble. Sound opened up, I could hear more details, subtleties, it was easier to recover details of the job that was done in recording and mastering studios. It was most obvious when I listened to the older recordings, mono if possible, with a lot of tape hiss. Obviously nobody listens to the tape hiss, but to music, but still a hiss is a part of the recording, it is its merit. And it shows any irregularities in frequency range even easier than music itself. The EPA-007 delivered perfectly flat frequency range, but with bit more of noise than my reference amplifier.
There are a lot of such sounding amplifiers, meaning emphasizing treble, probably even most of currently manufactured ones. If you start listening to it after another amp, that offers so rich, dense sound as Leben does, you'd probably start to think that its designer had some issues with his hearing. Each time I hear a strained sound, bright, 'shouty' treble, I turn such a device off and never turn it on again. When I started to listen to Phasemation for the first time, for first few seconds I thought it was the case. But after a short while I realized that it offered quite the opposite. There was a great grip over whole frequency range, tonality was very good – different than delivered by Leben, but at the same, high-end level. It so happened that I finished my listening sessions with Depeche Mode album, but I started it with a Martina L. Gore’s Counterfeit2 solo album, which is his second release, but it was not issued as Compact Disc, but as a Copy Control Disc. I mentioned that on some occasions before but I would like to do it one more time, as such „historical facts” might come handy for many Readers.

Copy Control Disc

The album of a main author of DM songs was issued in Europe not as a regular Compact Disc, but as a Copy Control Disc. Although you can't tell them apart just by their looks, signal on the latter was written in a bit different way. The CCD system was used since 2001 by two lebels – EMI and Sony BMG Music Entertainment (at the time these two companies worked quite closely together). The last discs with this system were released in 2004 (Sony) and 2006 (EMI). Copy Control did what its name said – it was supposed to prevent discs from being copied. Several methods existed, but the most widely used was the one introducing some incompatible data on the disc that would trick the computer's drive thus preventing it from reading all data on the disc properly. Although in theory this shouldn’t have effected CD Players, it actually did. What a paradox: the manufacturers of audiophile CD Players did their best to protect the process of reading a CD from any distortions, vibrations, radiation and so on, they also invented or at least initiated new ways of making better CDs, while the big labels did quite the opposite at the same time. Since the CCD did not fulfill Red Book CD standards labels couldn't place a Compact Disc logo on them. What's more, the international organization IFPI forced EMI to use a special marking on CCDs plus an information about what kind of devices would be actually able to read those discs. Sony was somehow able to avoid this obligation but they also stopped using Copy Control soon after that. There are two more things worth mentioning. First – this Copy Control System was cracked quickly and discs could be copied using many different software like Nero, for example. Secondly, software called Cactus Data Shield (CDS), that was used to protect CCDs, was created by an Israeli company Midbar Technologies.

The sound coming from CCDs is not too good, in most cases it's quite bad actually. The most obvious problem lies in treble that sounds quite thin and lacks definition. On many other occasions there is too much treble and it is too shouty. Since many albums were issued as both CD and CCD in the same countries you easily check that for yourself.
The more recent, top transports and decent D/A converters are able to deal with this problem quite well, but the problem still exists and is audible. If you play CCD in a system that includes some device that emphasizes treble already, listening might be very unpleasant. The Japanese amplifier surprised me with its balanced approach to the whole range, not just to treble. What I initially interpreted as emphasis or brightness, quickly turned into richness of details delivered at the same time. Not just details, but also information. I listened to Counterfeit2 without thinking even once that a label did everything in their power to make this album sound as bad as possible. The other range extreme is not very 'mature', not very rich, or at least not as much as with Leben. But it exists in perfect harmony with the rest of the frequency range. Listening to it you don't lack anything – you just perceive sound as a complete whole. What's more, as the attack phase is exceptionally fast, bass is precise, with great selectivity, it seems to be simply accurate.

Yes, I missed the richness of my tube amp a bit, but after a few days I came to conclusion, that it was a different way of presentation, but not worse at all. Sound might not be euphonious, as with Leben, but rather has an amazing clarity to it.
Another exceptional quality of this amplifier is spacing. It delivers sound surrounding listener, there is no „inside head”, or „between ears” presentation. And it doesn't come from some sort of signal manipulation that is used by some systems to achieve huge soundstage, but from a precision of presentation, that allows to create a large image in a very unforced manner. And who knows – this might happen to be the key feature for many potential buyers. The problem with headphone listening is that sound from one channel goes only to one ear. When you listen with speakers sound from both of them goes to both ears creating one image build basing on information collected by both ears, and it depends also even on the shape of a head, or ears. EPA-007 delivers music with a very good depth and width, but also with nicely defined middle of the stage, voices and instrument. It makes its presentation quite unique.

Settings and choices

To get such a tonality and spacing we need to use proper settings for each cans. This Japanese amplifier offers three sorts of settings. First of all we need to adjust the impedance for particular headphones. It really works – in each case there was only one clearly best setting. When I listened with any different than 'the one', sound was lacking its palpability, or was somehow muffled. The second setting, general gain, was actually useful only in one case – for HiFiMAN HE-6. The most obvious changes to the sound were introduced by the third setting, called: „Damp”. In fact with all cans at my disposal I preferred the sound with the knob turned left, to the „Soft” position. It delivered most palpable, warm voices, that were reproduced closely to the listener. When I used the opposite position, „Hard”, I heard everything like from bigger distance, bit muffled, bit harsh. I already told you which cans worked best with this amp for me: HD800 and HE-6. But I would add also 600 Ω version of Beyerdynamic DT-990 Pro and AKG K271 Studio but only when stock cable was replaced with Oyaide one. The sound of Beyerdynamic and AKG wasn't so opened like with two others, but it was a bit warmer and richer. So actually I I found myself chosing cans for particular music, or sometimes even for my mood.
My experience with other headphones, the ones I did not like with Phasemation, was different that usually. Usually if particular cans don't work with particular amp it is quite simple – sound is unacceptable and that's it. But with Phasemation a character of the sound changed differently with each model and for example AKG K701 did not sound warm, nor romantic anymore, and HiFiMAN HE-300 did not offer such nicely extended treble, and soft bass as they usually did. On the other hand AKG didn't sound „plastic”, which happens with some amplifiers. The Phasemation did its best with any cans I throw at it – it never just gave up, it delivered best sound possible in particular setup leaving the decision to the listener whether he liked it or not.

Oyaide HPC-X62
headphone cable

Headphones were always treated as a completed product, as w whole – starting from a plug, ending with drivers. The reason was simple – in most cases cables couldn't be replaced with others. And for some time nobody really thought that it would be a good idea to give users such a possibility. In recent years of a great headphones comeback, obviously related to still growing popularity of a PC-Audio it had to happen – some companies started to offer alternative cables for popular cans, and in many cases these cables offered better performance than original ones. One of this manufacturers is a Japanese company Oyaide.
Their cables are made of ultra-fine PCOCC-A conductors (80μ for a unit), twenty of 0.08mm wires are unified in a unit and the three units are grouped as a conductor which is geometrically-stable. The jack plugs are made in Japan. They are made of RoHS compliant brass. After careful machine barreling, silver (inner) and rhodium (outer) are directly plated on the contact pin. The other end of the cable can be terminated with different plugs. I chose a mini-XLR TRS version used by AKG for their Studio Series. I used it in this particular test with K271 Studio.

When selecting headphones for a Phasemation EPA-007 test, after short listening session I decided not to use AKG as they lacked some resolution and the treble was muffled. These cans are not easy to drive and usually they work best with studio equipment (see HERE. But the I listened them again after I replaced stock cable with Oyaide. Most of us agree that cables modify sound, but when it comes to headphones not many people actually try to replace stock cable with some alternatives as they don't believe it would work. You should try! When I replaced stock cable with Oyaide for AKG the sound became clearly better, more transparent, with better resolution. There was more energy in treble – what I mean is that there was more going on in this area. Before it sounded muffled, „plastic”, now it all became more palpable, instrument gained body, depth, that was not really 'visible' before. There is no exaggeration in a claim that replacing cable improved performance so much I could compare it to using more expensive model of AKG cans, while still delivering all that I liked so much about K271 Studio. So the replacement is not an option, it is a MUST!

Price: 300 zł/2,5 m


In general one could classify all headphone amps into two categories – the ones sounding warm, and the others sounding cold. To the first group I count in products from brands like: Leben, Yamamoto, Heed, Benchmark, Pro-Ject and some others, to the second group: Erzetich Audio, SPL and Ear Stream. In each case designers made some decisions about their products and the result was either warm or cold sound. EPA-007 might seem to belong to the second group. But it can be adjusted to headphones more like the amps from the first group. It offers amazingly clear sound, which describes members of first group, but is able to deliver the depth of each image, like the „cold” amps do. It delivers very fast sound, and both range extremes show a great resolution. Midrange is not as rich, dense, palpable and doesn't have a resolution of my Leben, but no other headphone amplifier ever equaled Leben in these aspects. The resolution can be improved, while keeping the same tonal balance, if we used balanced headphones and plug each channel separately to Phasemation. I tried that with HE-6 and I had to admit that it was the first time ever that these cans delivered sound with selectivity and resolution comparable to the top models of electrostatic STAX. In both cases I lacked some more bass extension and slam, but that's how electrostatic and HE-6 in balanced connection with Phasemation sound like. It is an exceptional headphone amplifier capable of working with any headphones.


The headphone amplifier was tested in an A / B listening test, with the A and B known. The reference amp it was compared directly to was Leben CS-300 XS [Custom Version] and Marantz NA-11S1, a file player that I reviewed for „Audio”, that was equipped with a very good headphone amplifier. I used three sourced, all with balanced outputs: Ancient Audio Lektor AIR V-edition CD Player, above mentioned Marantz, and Kuzma Stabi XL2 turntable with RCM Audio Sensor Prelude IC phonostage. The amplifier was placed on a Acoustic Revive's Hickory wood platform, a it used a Power Reference power cord of the same brand. Additionally I used Finite Elemente Ceraball that replaced standard feet. To connect HiFiMAN cans in balanced mode I used a Oyaide HPC-X62 cable. At the time of this test an alternative cable from Acoustic Revive was unfortunately not available.


Headphones amplifiers are usually quite small. Unless of course we are talking about regular amplifiers that drive speakers and are equipped with headphone amplifier or output just as additional feature. As some examples of such amps I would name: Cary Audio CAD-300-SEI, Leben CS-300 XS, Leben CS-600 and Linear Audio Research IA-30T, and with one exception of SPL Phonitor 2730. Other amplifiers are rather small in size – they don't need to produce some huge output power, do they?

The Japanese Phasemation EPA-007 fits the profile. It measures 220 x 57 x 234 mm and weights 2kg. The whole chassis is made of aluminum, and the front panel has some extra thickness. Front panel sports three knobs, two toggle switches, and two headphone outputs (for 6,3 mm jacks). The largest knob is a volume control, the smaller ones allow to set: „damp” (Soft-Hard), and adjust impedance for particular cans. For the latter there are three ranges to chose between: up to 200 Ω, from 200 to 500 Ω, and above 500 Ω. One of toggle switches allows to change gain. For cans with impedance below 100Ω we should chose a Low setting, for the rest the: High one. I learned during my listening sessions that for such ultra-low impedance cans like HE-6 the High setting was better. The other switch decides whether signal is delivered to both outputs (for balanced headphones), or only to one of them. EPA-007 is a fully balanced device. And to use its full potential you should use cans with separate cable runs for left and right channel, with 6,3mm jacks of course.
There are two sets of inputs - XLR and RCA. I definitely preferred the former over the latter, even with headphones with cable terminated with single jack. You should take into consideration that input impedance of this device is not too high, it's just 10 kΩ, so you need to chose your source carefully. On the back panel there is a IEC power inlet integrated with the main on/off switch. There is a small LED indicating whether the device is on. Amplifier sits on very small, plastic feet, that should be replaced as quickly as possible with something more substantial.

Specifications (according to the Manufacturer)

Input impedance (RCA/XLR): 10 kΩ/20 kΩ
Headphone input impedance: 16-600 Ω
Frequency response: 20 Hz – 100 kHz (-0,5 dB)
Noise: 50 μV
Channel separation: -90 dB
Power consumption: 1,5 W
Dimensions (WxDxH): 220 x 57 x 234 mm
Weight: 2 kg

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