The HIFiMAN EF-6, may well be described as the iron fist in a velvet glove. It has all of the attributes of power and control without the common accompanying detractors. If you have efficient speakers, you may kill two birds with one stone by hooking up the four pin balanced connection with something like the Stefan Audio Arts balanced to spade convertor. This amp is absolute joy on the Sennheiser HD-800 and even more so on the HiFiMAN HE-6...either brings magic to the table. It also can serve as one lovely preamp with uber gain. The reviewers agree.
"Fanciers of the Audez'e LCD-2 tend to find the HD800 too flighty and top-heavy. They would have found that the 800/EF6 combo brought the presentational style far closer to their ideal, albeit with still more treble extension and energy and less bloomy bass...Aside from sounding less grippy and more relaxed and grounded, the EF6 had a measure of what valve aficionados call moisture. The amp casts a very wide soundstage whose side-to-side lighting is expansive and even. This relaxes the usual central skull focus. If in its headfi class the EF6 is a giant on size and power, it's clearly the gentle benign sort. For HE-6 fans all is finally as it should be. Now they truly have one of the very best headphones money can buy. (with the EF-6)
“I don’t know if I have the vocabulary to describe this,” he said. “It blows me away how clean they sound. There’s no distortion at all, which really makes me want to listen. When the bass hits it has that perfect sense of the acoustics of the instrument, like hearing a live bass drum. My only disappointment is that the midrange is a little low in level, but I didn’t mind it because the highs and lows are so clean, and it all comes together beautifully. Short of being in the studio with the musicians, this is it. I really enjoyed the bass.”
I noticed also that it sounded smoother through the EF-6, with more detail and definition in the upper midrange, especially. Through the V-Can, it sounded comparatively dull and crude — still good, just not as good. Same with the guitar and chanted vocals in “Trembling Hands” from Explosions in the Sky’s Take Care, Take Care, Take Care. Without changing the overall tonality of the tune, the EF-6 simply seemed to find more information, more detail, more life in the midrange.
-Brent Butterworth - Sound and Vision
"As with certain Rolls-Royce automobiles, the power output of HiFiMAN’s EF-6 headphone amplifier could best be described by one simple word: “Adequate” (where we interpret the word to mean not just having enough, but more than enough power for any headphone load one might ever wish to drive).
But there’s more to the EF-6 that wattage alone, because this pure Class A design also offers speed, agility, clarity, low-level resolution, and plenty of refinement, plus a rare ability to help music sound richer, more vivid, approachable, and involving than it otherwise might. In short, the reason to consider buying and EF-6 involves not only the fact that it can drive just about any load, but that it can also pull you closer to your music."
AV Guide-Chris Martens
Volume: Hand-made Step Attenuator
Power Supply Design: CLC filter
Weight: about 24 lb (10.75 KG)
Dimensions: 13''(330 mm)Wide *12.2"(310mm)Deep *4.1"(105mm)High
THD: 0.03% (1w and 1KHz)
S/N: 95 DB
Max Output: Class A 5W at 50 Ohm