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Portable music player + headphone amplifier + headphones
HiFiMAN HM-602 + EF-5 + HE-4

Price: 439 + 499 + 449 USD

Manufacturer: Head Direct Corporation

Fang Bian
fax/voice mail: 1-718-766-0560



Country of origin: Country of origin: Chiny

Text: Wojciech Pacuła
Pictures: Wojciech Pacuła, HiFiMAN

The name Head Direct Corporation is quite meaningful. This company deals only with headphones and electronics working with headphones. The brand-name HiFiMan is also quite special. For this review we have received one of the novelties – HE-4 headphones – not the top of the line but sporting many solutions taken from the most expensive model.
We have also received a head-amp – very nice two-box one EF-5 with external power supply DY-1. It sports a tube input and is capable of driving even very difficult headphones like, e.g., HE-4 – have I mentioned that these are orthodynamic ones? I probably haven't, so these are planar, orthodynamic headphones which means that design is somehow similar to that of magnetostatic speakers. They feature quite low sensitivity and are quite difficult to drive so not all head-amps will be able to do that. To deal with that HiFiMan amplifiers offer high gain. These are true „earspeakers” (using Stax name – it is as if we wore miniature planar speakers like Magnepans.

There is also the last piece of this puzzle – the source of signal. This manufacturer won hearts of many customers, although those who wanted some from outside mainstream, with HM-802 portable player. It is quite a large device, featuring legendary PCM1704 DAC chips and sporting removable head-amp module, which allowed to replace it with other, made by different company. HiFiMan provided customers with schematics encouraging them to experiment, to try to find their own best solution. Quite a different approach to the customers, isn't it? The reviewed model, although smaller in size, has been designed equally well, if not better… This device features TDA1543 Philips DAC - a non-oversampling chip, there is no up-sampling and only a very simple low-pass filter in the output stage. Super! There is one downside of this solution – sampling frequency is limited to 96 kHz, but we gain something at the cost of something else – that's some compromise. This is a SD cards player capable of playback of mp3 and FLAC files with resolution up to 24 bits / 96 kHz. It features large, color display but it won't display covers – simply there is no operating system and no microprocessor. Internal memory is limited to 16 GB (limited if you consider how big could hi-res files be). This device can also operate as D/A converter with mini-USB input so it could work with PC as a source.

We received a complete system for our test – signal from mini-jack output of the player went via iChord cable made by The Chord Company to the head-amp, and the latter drove headphones. So part of the time that was the system I listened to. But these are also three separate devices so I had to check each of them and the results were even more interesting.


Recording used during listening sessions:

  • Audio Accesory - T-TOC Records High Quality Data Master Comparison, TDVD-0002, DVD-R, ripy 16/44,1, 24/96, 24/192 WAV.
  • Antonio Forcione & Charlie Haden, Heartplay, Naim Label, FLAC 24/96.
  • Brenda Lee, Reflections In Blue, Decca/Universal Music Japan, UCCU-9645, SHM-CD.
  • Brian Eno, Craft On A Milk Sea, Warp Records, WAV 24/44,1.
  • Carmen McRea, Book of Ballads, Kapp Records/ Universal Music Japan, UCCU-9634, SHM-CD.
  • Carmen McRea, Torchy!, Decca/Universal Music Japan, UCCU-9633, SHM-CD.
  • Cassandra Wilson, Silver Pony, Blue Note, 29752, CD;
  • Charlie Haden & Antonio Forcione, Heartplay, Naim Label, 24/96 FLAC.
  • Chris Connor, Witchcraft, Atlantic/Warner Music Japan, WPCR-25166, CD.
  • Depeche Mode, Ultra, Mute, DMCDX9, Collectors Edition, CD+DVD.
  • Ella Fitzgerald, Ella in a mellow mood, Decca/Universal Music Japan, UCCU-9642, SHM-CD.
  • Freddie Hubbard, Open Sesame, Blue Note/Audio Wave, AWMXR-0012, XRCD24.
  • G. F. Haendel, Messiah (Dublin Version, 1742), Dunedin Consort&Players, Linn Records, CKH 312, FLAC 24/88,2.
  • Harry Belafonte, Belafonte at Carnegie Hall, RCA/Sony Music, 7783322, LPCD-M2 Mastering, No. 0953, HQCD.
  • Helge Lien Trio Hello Troll, Ozella Music, OZ021CD, FLAC 24/96;
  • Jeri Southern, The Southern Style, Decca/Universal Music Japan, UCCU-9643, SHM-CD.
  • Jim Hall, Live!, Horizon/A&M Records/Universal Music Japan, UCCM-9225, CD.
  • John Abercrombi&Eddi Gomez, Structures, HDTracks, FLAC 24/96.
  • John Coltrane, Blue Train, Blue Note/Classic Records, HDAD 2010, DVD-V 24/96 + DVD-A 24/192 + FLAC.
  • Linda Ronstadt, What’s New, Elektra/Lasting Impression Music, LIM PA 046, gold-CD.
  • Maria Peszek, Miasto Mania, Kayax, 007, CD;
  • Norah Jones, …Featuring, Blue Note, 09868 2, CD.
  • Recoil, SubHuman, Mute, LCDStumm279, CD+DVD 24/44,1.
  • Santana, Abraxas, Columbia/Mobile Fidelity, Collectors Edition, No. 06452, UDCD 775, gold-CD.
  • Stan Getz & Joao Gilberto, Getz/Gilberto, Verve, 24/96 FLAC.
  • Suzanne Vega, Close-Up, Vol 1. Love Songs, Amanuensis Productions/Cooking Vinyl, COOKCD521, CD.
  • Zbigniew Namysłowski, Open, Polish Jazz, vol. 74, SX2539, pliki „master”, 16/44,1, 24/96 WAV.

Japanese issues available at CD Japan.

HiFiMan HM-602 + HE-4

As expected this player clearly shows the differences between 16 and 24 bit files, both with external amplifier and its own. Driving head-amps directly it sounds in a very open, clear way. No doubts sound quality is much better than when delivered by iPod.
What surprised me most was outstanding clarity of the sound. When I played some pieces to my friend he noticed the same thing but than he said he felt like there was too much energy in the treble. And it was not about it sounding to harsh or too bright as we both agreed that tonal balance was good. He wasn't used to such a clear presentation and that was the case. He asked this question when he took off headphones, than he put them back on and kept listening. After some more listening he changed his mind - „wow, that's how it must have sounded in studio” he said– „ I could hear each murmur, each tonal or intonation change, each time finger touched a string and so on. It was so audible because microphone enlarged it all”. I had to agree – I could hear amazingly lot special with 24/96 files but also with CD rips. As you know microphone works bit like magnifying glass so it is not a flow of a system showing it. I would even say that only when you can hear this effect the work of the system is done (at least in this aspect). As long as everything is small, this – it doesn't make any sense as the problem than lays with the recording and not the system.
As already mentioned – it is incredibly clear sound with quite strong treble – strong meaning open, wide and not just huge in volume. There is a lot of sounds, these are very coherent and always presented in the same order which means that when you change a recording, it has its own character but the way of presentation stays the same. Bass is not overwhelming in terms of volume but its quality is astounding as for what can be delivered by headphones. These headphones offer one of the most precise, clear presentations of bass that I know. Sometimes, like when listening to 24/44.1 rip of SubHuman by Recoil, I missed this strong bass foundation, same one that effected in extremely fabulous richness of the sound of Sennheiser HD800 with Leben CS-300 XS (Custom Version). Probably that is exactly why phantom images (considering that this is headphone presentation) were bit smaller than from my reference system. But the clarity, dynamics, speed – in all these aspects HiFiMan had an advantage.
To use HM-602 with HE-4 I had to use „High Gain”option. Even though it wasn't really enough for recordings made with full dynamics which made them sound bit more quietly like e.g. Heartplay by Antonio Forcione&Charlie Haden (24/96), or Structures by John Abercromby&Eddie Gomez (24/96). Don't get me wrong – I had no problem with listening to them but I wish I could do that bit louder. When listening to CDs, but also to pop or rock 24/44.1 rips (like Depeche Mode ones issued as Collectors Edition) I had an impression of presentation being even „overcharged”. But when listening to jazz recordings I lacked sometimes some dynamics.

HiFiMan HM-602 + Sennheiser HD800

To use Sennheiser HD800 I had to choose „High Gain” setting too. This system didn't sound so clear and precise any more – in these aspects HiFiMan's headphones are simply way ahead of any classic, dynamic headphones – and remember that HD800 had been, up to this point, my reference ones also in these particular aspects.
Using German headphones effected in more relaxed sound, not so precise treble and with more focus in the midrange. Bass was stronger but not so extended. I think it is how this player builds the sound. It is capable of delivering extremely precise midrange and treble, with no sign of brightness or harshness – just perfect. Low range is also precise but not that extended as it could be, at least if we use large headphones or linear output. I found another advantage of Sennheiser – soundstage is wider and deeper – obviously HE-4 have some limitations in this aspect.
I also paired for a short time HiFiMan with AKG K701, but I didn't like the effect. There was too much emphasis on upper midrange which ruined coherency of the whole range. I believe that HE-4 have the best control over midrange and are capable of delivering more information in more natural way than Sennheiser or AKG headphones.

EF-5 + HE-4

Performance of the headphones connected to EF-5 amplifier (with CD Ancient Audio Air as a source of signal)) is quite similar to the one of same headphones paired directly with HM-602. Sound is very clear, dynamic. The external power supply adds more flexibility to volume control and thus there is no audible compression of dynamics even with „Low Gain” setting. Very quickly I realized that there was a distinct attribute of EF-5's sound that, in my opinion, should rather make you look for other headphones.
In my opinion tonal balance of HiFiMan's head-amp is slightly shifted up. It doesn't make it sound bad but I craved for richness and density of presentation of my reference system. On the other hand there is still fantastic speed, clarity and dynamics. The most important difference (at least how I saw it) is the intensity of presentation – with HiFiMAN's system I felt like as if the sound was uploaded directly to my brain – Peszkówna on Miasto Mania had extremely strong voice, different additional effects were presented on a very wide soundstage. That's what one should expect when listening to the music via headphones. There is one flaw still available – bass extension that wasn't good enough for me.

EF-5 + AKG K701

Searching for the best set I tested all headphones at hand - Sennheiser HD800 (bit too much treble for my taste), Ultrasone PROLine2500, Beyerdynamik DT-990 Pro (original edition), and last but not least AKG K701. I found this last ones to be the best match for EF-5. Sound was very creamy, presentation of human voices was outstanding, and it never got too bright. It was really colorful, sometimes rather in pastel colors. Tonal balance was moved rather towards lower midrange and thus even though bass still wasn't extended enough, I could finally enjoy the presentation without complaining.
That's probably why during first days of listening I really enjoyed mostly vocal recordings, many of them in SHM-CD format from Decca label, including Ella Fitzgerald Ella in a mellow mood, Carmen McRea Book of Ballads and Torchy!, Jeri Southern The Southern Style and Brenda Lee Reflections in Blue. I realize that's a lot of titles but I wanted to give you the right idea – sound was … delicious – creamy but also precise, with pastel colors on one hand but with great definition too. I really liked dynamics delivered by AKG as it's not really their specialty. All above mentioned albums, with the exception of Brenda Lee's, were recorded between 1954 and 1958 and are simply fabulous. System build with HiFiMAN and AKG the right one to deliver such a fabulous music.

HE-4 + Leben CS-300 XS (Custom Edition)

This system was the second one (the first one was Sennheiser HD800 + CS-300 XS) that could be for me, at least in some aspects, a reference system. Not that I suggest these two were the best in the world, but these were good enough in so many aspects that I could refer other systems to them.
HE-4 have an advantage over Sennheiser in terms of resolution and speed. I guess these features result in the outstanding transparency. I needed to listen to this system just once to realize that it could become an absolute reference in this particular aspect. It was also incredibly liquid sound. Presentation of bass was also clearly better than with EF-5. It wasn't still that extended as with Sennheiser, but it was already good enough not to miss it anymore.
I missed a bit the liquidity, continuity of the HD800 sound, but I don't know any other headphones that could bit Sennheiser in this aspect. They also show bigger phantom images, unlike HE-5 that tend to decrease those and focus on the middle of the soundstage.

HiFiMan HM-602 + EF-5 + HE-4

Listening tho the whole delivered system I left for the very end as I had to wait for Chord mini-jack / 2 x RCA cable. After listening to all elements of this system in different configurations I already had opinion about each of them and I thought that listening to them put together as a system would only confirm my observations. I was wrong. Each of HiFi MAN's products is really good, in some aspects they are even outstanding but to get the best of them you need to carefully choose the rest of the setup.
The full system somehow sums up all and emphasis the advantages of each element. The first recording (played from 24/44.1 file I just bought online) Craft On A Milk Sea by Brian Eno sounded great. I couldn't believe that I was listening to the music from portable music player combined with small head-amp. Only in this particular setup HE-4 delivered very well extended bass range, and incredible, hard to match resolution and transparency. This system delivers extremely coherent, liquid sound. It was surely one of the very few best (headphone) systems I'd ever heard. Sennheiser HD800 with Leben CS-300 XS (Custom Version) offers bigger presentation with deeper, better defined soundstage but the resolution is an advantage (but small margin but still) of HiFiMAN's system. STAX electrostatic systems might be slightly faster and they might offer bit better resolution of the midrange, but can't deliver such a rich timbre as the tested system. Sennheisers with Leben might sound more authoritatively with some very dense recordings, but that also an advantage by a small margin.
At the cost of 1500 EUR you might have an incredible, high-end system. You get a player that allows you to interchange head-amp modules (but anyway you need your music in FLAC files), you can “upgrade” or at least change the sound of amplifier by tubes rolling. I must say I loved this system as it stayed with me as my second reference system. I would compare it to buying new books – you already have a lot of great ones but as soon as you read another great one you need to buy it to read it again and again or to wait for the next part. That's what happened with me and HiFi MAN's system. I highly recommend it to all headphone fans!!!


HiFiMAN's products are excellent. There are not cheap. The player can't compete with iPod or iPhone in terms of ergonomics and the look (but what really can?!). It is simply not so well-thought-out. It requires also some external data storage (16 GB internal memory isn't too much, especially if you use hi-res files). It's performance is though excellent which should be enough to forget about its flows. You should have hi-res files if you want to use this player as these will sound much more liquid, more precise, better.
EF-5 head-amp sounded great with AKG headphones. Its tonal balance is slightly on a bright side so you should be aware of that when choosing cables, source device or headphones. With AKG it creates true synergy.
Last but not least – headphones – for me the most interesting part of delivered system. These offer fantastic resolution and dynamics. No dynamic headphones offer sound like this one. Their tonal balance is slightly on the bright side which suggests that you need to find a proper head-amp for them. With the right amp they will play faster and more precisely than electrostatic headphones (except for the most expensive STAX), with better dynamics and more coherency.
It's the system that ultimately delivers the sound. Resolution, depth, involving presentation – it comes from the whole system. It is easy to recommend HiFiMAN's system but also single items, really, really easy.


HiFiMan HM-602

HM-602 is a portable music player, featuring 16 GB FLASH memory. You can also play files from external FLASH SD card (up 32 GB size). The circuit is build around Fuzhou Rockchip Electronics Co chip - RK2706RB. It's a two-cores, very robust chip that is capable of decoding pictures, playing video, reading ebooks, but here manufacturer used only some of its potential. This player can also act as D/A converter with USB input. This type of signal must be decoded first – this is done by USB Audio CM108AH C-Media controller. It is not the best on the market but should do its job just fine.
Player's casing is quite big – surely thicker than iPod Classic's, although bit shorter. Its size is directly connected to its internal design – it's not a SMT, but rather more classic mount technology. It features ingenious NOS Philips TDA1543 DAC chips. One of their features is a possibility to turn off oversampling, and manufacturer used this possibility. If you could spare some time please have a look at Mr Ryohei Kusunoki's (47 Labs) article HERE - it will explain a lot. The chip itself is not perfectly linear and is bit noisy (comparing to some modern products), but many people find its sound … seducing. Manufacturer used also “classic” opamps – OPA2107 in headphones output, and OP275 and OPA2604 in linear output. Mr Fang, company's representative, confirmed that the amplifying section is almost the same as the one used for HM-802. There is a choice between “normal” and “high” gain setting executed with a simple switch allowing to adjust gain for particular headphones.

This device is well equipped – there are analogue outputs (linear and for headphones jack), plus two mini-USB ports. One of them can be used to connect the player to a computer to download music files. The other one is also used to connect HM-602 to a computer but this time for it to serve as DAC – cool solution!
There is a color display showing information like the name of the file and some more information from its ID. No covers obviously. You will get the length of the word but no sampling frequency. Player is equipped with external power supply to charge its internal rechargeable cell.

Ergonomics is obviously not this device's priority. It fits a palm quite well, you don't really feel its weight, but user interface is not as friendly as it could be. There is one “easy” manipulator though – it's a push-button in the middle that is used to start and stop playback.

Specyfikacja techniczna:
D/A Chip: TDA1543
LPF Op-amp: OP275, OPA2604
Headphone Amplifier Op-amp: OPA2107
Frequency Response: 20-20K Hz
Distortion: 0.09%
S/N: 92 DB
Stereo crosstalk:74 DB (Lineout)
Headphone Amplifier
Output level: 1.1v at 32 Ohm; 2.2v at 150 Ohm
Max Output: 30mw at 32 Ohm; 26mw at 150 Ohm
Size: 62mmX103mmX26.5mm or 2.4 X 4.05 X 1.04 Inch
Weight: around 200g
On board Flash: 16GB
Battery time: 9 to 10 Hrs
I / O: Headphone Output; Line Output; USB Data Exchange; USB DAC Input; SD card (up to 32GB)

HiFiMan EF-5

Headphone amplifier EF-5 is the top device of its kind in this manufacturer's portfolio intended to drive all HiFiMAN's planar headphones – the ones I tested - HE-4, as well as the top of the line HE-6. It includes two main modules of the same size – power supply and amplifying stage. The latter can be easily recognized by a Fullmusic 12AU7 double triode standing out, that works as input buffer. There is also quite powerful input stage with OPA275 chips driving powerful output transformers (there are four per channel and these are covered with large, gold heatsinks). Amplifying stage is mounted on small PCB, that is plugged into the main PCB with golden pins. Miniature Alps pot is responsible for volume control. The main PCB is in fact a power supply section – a really advanced one. There is a switch on the top of the device that allows to choose between „High Gain” and „Low Gain” setting. The latter should be suitable for most headphones. On the front there is on/off button, output for a headphone jack, and a small knob for volume control.
Amplifier is fed from a DY-1 power supply equipped with IEC socket. Obviously it might be used also for some other device and the output voltage is selectable - 16 or 18 V AC. In side there is a large toroidal transformer.

Technical data:
Opamp: OPA275
Tube: Fullmusic 12AU7
Frequency Response: 20-30K Hz
THD+N: less than 0.2%
S/N: more than 95dB
Input impedance: 50K Ohm
Output impedance: 2–2K Ohm headphones
Output signal strength: up to 15 Volts at 32 Ohm
Input: RCA*1
Output: 1/4 headphone jack*1
Dimension: 110mm(W)*50mm(H)*270mm(D),
Weight: 3 kg (including packing)
Accessory: 12AU7 tube, DY-1 power supply, compatible from 110v to 240v
Hand built

HiFiMan HE-4

As Mr Fang, HiFiMAN's representative, said in the “” article (HERE): „Our planar headphone project started in early 2009. Because one can source the very best magnets right here in China, we decided to create a high-end planar headphone. Our first prototype was only 4 ohms and we had to add a resistor to the driver to make it work with headphone amplifiers. Then we learnt how to print a thinner voice coil onto the Mylar diaphragm. The thinner the coil, the higher the impedance. The HE-5 was 25 ohms, the HE-5LE is 38 ohms.” HE-4 have exactly the same impedance. Mr Fang said that HE-4 was the single end version of HE-5LE with very similar sound signature. Since magnets used in HE-4 are 50% smaller from the ones used for HE-5LE, the first of them are much lighter (350 g). Their design is quite special – they sport a Grado-type fixed leather-clad and padded bridge. With headphones we receive three set of cables (3m each) that are plugged to headphones with very nice, gold plated plugs. One sports at the other end a “big jack” (Ø 6,5 mm), balanced portable headphone cable sports 3.5 mm 4-pin plug (for your mobile phone), and the third one sports plain small-jack (Ø 3,5 mm). You want to use different cable (like from Cardas or Oyaide)? No problem – in the box you will find also some plugs you can mount on these cables.

Technical data:
Frequency range: 10 Hz-60 kHz Impedance: 38 Ω Sensitivity: 86 dB Weight: 350 g

Head Direct Corporation
fax/voice mail: 1-718-766-0560



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  • CD player: Ancient Audio Lektor Air (previous it was Prime, tested HERE)
  • Phono preamplifier: RCM Audio Sensor Prelude IC (tested HERE)
  • Cartridges: Air Tight Supreme, tested HERE, Miyajima Laboratory Waza, tested HERE.
  • Preamplifier: Ayon Audio Polaris III with Re-generator Power Supply; version II tested HERE)
  • Power amplifier: Tenor Audio 175S, tested HERE and Soulution 710
  • Integrated amplifier/headphone amplifier: Leben CS300 XS Custom version (reviewed HERE)
  • Loudspeakers: Harpia Acoustics Dobermann (tested HERE)
  • Headphones: Sennheiser HD800, AKG K701, Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro, 600 Ω version (reviewed HERE, HERE, and HERE)
  • Interconnect: CD-preamp: Acrolink Mexcel 7N-DA6300, article HERE), preamp-power amp: Wireworld Platinum Eclipse
  • Speaker cable: Tara Labs Omega Onyx, tested HERE
  • Power cables AC (all equipment): Acrolink Mexcel 7N-PC9300
  • Power conditioning: Gigawatt PF-2 Filtering Power Strip (reviewed HERE)
  • Audio stand Base – under all components
  • Resonance control: Finite Elemente Ceraball under the CD (article HERE)
  • Pro Audio Bono platform under CD