Hifiman HE-6/EF-6: An Elite Headphone System, Under One Roof
Not that long ago, even the best headphone systems nearly always had a glaring deficiency or two, and few, if any, were all-around performers that could transition from musical genre to genre, let along into home theater. Sonic colorations abounded, and choosing a high-end headphone rig was almost as much about choosing which flaws to accept as which strengths to embrace. However, in recent years, a flurry of new elite headphones have come to market, largely with far fewer compromises than their predecessors. Today I look at one of the new guard, the Hifiman HE-6 headphones as powered by the new Hifiman EF-6 amplifier.
The HE-6 stands at the top of Hifiman’s line of planar magnetic headphones, with the largest driver area of any model. Hence, the HE-6 is an extremely power hungry headphone, with an efficiency of only 83.5dB/mW at 50ohms impedance. This demands a powerful, sophisticated headphone amplifier with low output impedance and high drive current, in order to maximize the sonic performance.
The EF-6 is just that, a full class-A headphone amplifier with discrete output topology, capable of delivering a full 5W of power into the HE-6’s 50 ohm load (enough power to drive the HE-6 over 110dB, sustained with headroom for dynamics). Only a few headphone amplifiers of similar discrete, class-A heritage exist, and they are nearly exclusively the realm of DIY experts, rather than polished, off-the shelf products.
The side panels of the EF-6 serve as heatsinks for the output transistors, as they have on many other class-A solid-state amplifiers. After many hours of continuous use, the temperature of these heatsinks remained stable at approximately 30 degrees Fahrenheit above ambient room temperature, the highest temperature I measured at any point on the amp’s exterior.
The large front volume knob is linked by extension to a stepped attenuator near the rear of the chassis. The knob turns firmly with deliberate stops for each volume level. The amplifier’s front also features push-buttons for power on and relay-controlled input selection, as well as blue LED’s to indicate the active input. The power LED is purple when the amp is turned on, to indicate a warm-up period, and turns blue after ten to fifteen seconds as a relay clicks, indicating the amp is ready to play.
The EF6 includes front 1 / 4” and 4-pin XLR headphone outputs, and a 1/8” auxiliary input jack for convenient connection of portable devices. The 4-pin XLR output is key, as the HE-6’s standard copper cable is terminated with that very connector. While the HE-6 is not a balanced amplifier, the front XLR connector is a convenience for HE-6 (as well as K1000) owners, who need not connect an adapter cable with bulky inline XLR connectors when using this amp. The rear of the EF-6 features dual RCA inputs (toggled by relay from the front selector switches), as well as one pair of RCA preamp outputs.
For the purposes of this review, the EF-6 was fed by a Hifiman HM-801 DAC/PMP. Boasting a PCM 1704 multi-bit DAC chip, among other noteworthy parts, it is superior to every home DAC I’ve owned (in the $1k-2.5k range), and a worthy companion to this headphone system.
The most fundamental characteristics of the HE-6/EF-6 sound are precision and control. The system maintains a toe-tapping enjoyable character, while fleshing out layer after layer of detail. Often these sound characteristics are thought to be mutually exclusive, but this headphone system manages to straddle the lines between musical and analytical, forward and laid-back, neutral and natural.
The bass is remarkably taught and well-controlled, even down to the depths of 20hz and beyond. Whether pounding timpani or taiko drums, electronically modulated beats, or explosive Hollywood effects, the bass is as powerful, lifelike, responsive as I’ve heard from a headphone, all without overshadowing or bleeding through into the midrange. Driven by the EF-6, the HE-6 maintains this bass control up to and beyond any volume my ears could tolerate, unflapped and without distorting.
Unlike many headphones, the bass of the HE-6 is not boosted beyond neutral, and delivers a palpable thump through the tremendous dynamic capacity of its’ massive drivers. Many high-end headphones of the past, even when well driven, produce a slow and flabby bass by comparison. The visceral depth and punchy quickness of the HE-6’s bass becomes apparent quickly, then addictive.
Transitioning to the midrange, the HE-6 maintains a very well-balanced and open sound, allowing the minute details of performance to come forward. The midrange is nothing if not precise, every note clear, distinct, and perfectly measured. The HE-6 projects a very live sound, without being too forward, or ever becoming shouty, echo-y or sibilant. Textures are palpable, and acoustic recordings shine with realistic snap and energy. The treble is extremely detailed, yet smooth, with great extension that helps produce a very well-imaged soundfield.
Imaging is a strength of the HE-6, and it performs with the best headphones I’ve heard in this regard. It is most fruitfully put to use when listening to multi-channel material through a Smyth Realizer. Whether multi-channel SACD’s or the lossless audio tracks from the latest Blu-Rays, the combination of the HE-6, EF-6, and Realizer creates an amazing virtual surround sound experience. The depth of the soundfield is quite remarkable, just close your eyes, and you can almost reach out and touch the speakers, across the virtual listening room.
The Impact of Pads
The choice of pads will be a question of preference, but fortunately Hifiman provides both options for your experimentation. The factory installed pleather pads provide a slightly warmer sound with a bit more presence in the low- to mid- bass, and slightly less treble energy. The soundstage presentation is a bit less wide left to right, but no less deep nor well-imaged. The velour pads, supplied with the HE-6’s accessories, imbue a slightly leaner tonal balance with a wider soundfield left-to-right. Or, put another way, if the HE-6 with velour pads is a front-row listening experience, the HE-6 with pleather pads is a few rows back.
In general, I prefer the sound of the HE-6 in conjunction with the velour pads, even if it is somewhat less forgiving of substandard recordings. It should be emphasized that changing the pads does not drastically alter the overall sound of the HE-6, and characteristics like supremely fast, tight bass and wonderful layering and instrument separation remain hallmarks. The pads should provide a useful tweak, allowing the user to minutely tailor the sound signature to their own preferences.
My past experiences with the HE-6, using powerful, but lesser, headphone amps, like the Grace M902 or a Gilmore Dynalo based amp, yielded a sound that was not quite so impressive. Bass certainly lacked the power and authority I have come to expect from the HE-6, using it with the EF-6. Imaging also suffered by comparison, still performing well, but without quite the level of depth and precision. Further, the overall sound was a bit duller, more veiled, less upfront and involving. Without question, the HE-6 demands an amp on the level of the EF-6 to reach its’ true potential.
Powered by the EF-6, the HE-6 stands up well in a field of contemporary headphone juggernauts. A common comparison is the Audeze LCD-2 and LCD-3, the alternative in planar magnetic headphones, with a markedly different sound presentation to the HE-6. The Audeze strike me as sounding less expansive and layered than the HE-6, with a more prominent bass, which makes for a more intimate sound, as if seeing a band in a club rather than a theater. Also with a smaller, but brilliantly imaged soundfield is the JH Audio JH3A system, a portable pro-audio studio. On the other hand, the new flagship Stax SR-009, in conjunction with the Headamp BHSE amplifier, throws a massive soundfield, as if listening inside a grand concert hall.
All of these grand new headphone systems perform on a level beyond that of forefathers like the HE90, R10, L3000, Qualia 010, and so on, as they offer fewer sonic compromises in their respective presentations, not to mention less fuss and system matching to optimize. Now it is a question of which style of presentation best suits the listener, rather than which compromise would they be most willing to live with. Having heard them all, most quite extensively, without question I would rather have an elite headphone of today, than an elite headphone of the past.
The Hifiman HE-6 and EF-6 are a shining example of the great recent progress of headphones, driven by rising newcomers, and market stalwarts alike. That it is now possible, for under $3000, to quickly and easily assemble a headphone system which sonically outperforms the $5000 and up systems of five to ten years ago is quite a feat indeed. While headphones themselves can be a very personal, and often less than rational decision, there is no denying that the readily available HE-6 is the equal, if not superior, to many of yesteryear’s best headphones, which were often produced in limited quantities, hard to find, and more expensive. Now, paired with the EF-6, a headphone amplifier with few peers, and even fewer easily obtainable peers, it is clear that one of the world’s elite headphone systems can now be found under one roof: Hifiman.
Edited by Iron_Dreamer - 7/14/14 at 11:11am