Performance

Head-Direct’s HiFiMAN HE-6 headphones are some of the most power demanding headphones on the market today. They require a carefully selected amplifier to sound their very best, which can prove a challenge since they are ruthless in their presentation when it comes to bad source gear, they simply reveal all deficits. For this review we have tested them on our old and trusty Head-Direct EF-1 amplifier along with Marantz 1090 and a Denon PMA-QS1 through the new Head-Direct Speaker Adapter. The source used was a HiFiMAN HM-801.

On the EF-1 amplifier the HE-6s sound quite a lot better than the HE-5LEs which is one of the best entry level high-end headphones available. The HE-6s have a more pronounced yet sweet high-end which really brings out cymbals and high level harmonics from guitars. It is clearly noticeable that the HE-6s are superior when it comes to treble extension and control. The bass is even deeper than the HE-5LEs, and the midrange is a tad less hot which is a good thing. The HE-6's brilliance lies in its remarkable detail oriented sound along with a deeper sound stage than the HE-5LEs.

The midrange is very balanced compared to the bass and there is very little coloration of the midrange. Due to the less treble roll off the midrange seems less pronounced.
Bass extension wise these headphones are remarkable. They are able to produce some real rumble without having an elevated upper bass or mid-bass for that matter. Compared to the HE-5Les the HE-6s are slightly more athletic in the sense that they are better at reproducing details in complex passages. The details are also highlighted because of the HE-6s more even frequency response.

The sound stage performance was not that good with the old HE-5LE design, however, on the HE-6s the small annoyances seem to be fixed to some extent. The sound stage appears noticeably deeper and the perceived space between instruments is larger as well. This could be due to the various tricks that Head-Direct have applied to the cups of the HiFiMAN HE-6s. Even though you are positioned further away from the music it has not affected presentation detail level. Keeping that in mind the HE-6s are still nowhere near the Sennheiser HD800s in terms of sound stage performance, the HD800s retain the spacial representation crown by a fair margin.

Treble wise the HE-6s manage to squeeze just a little more detail out of the music than the HE-5LEs. That combined with the fact that it has a less rolled off treble means that the HE-6s high end is incredibly rich to listen to without being over the top like that of many higher end Grado headphones.

Compared to the Sennheiser HD800s which we reviewed a while ago these are much more musical. The HD800s excel when it comes to sound stage, but they lack a little warmth and a bit of bass in order to be truly satisfying to listen to in the long run. In a world where one cannot have the sound stage of the HD800s and the bass of the HE-6s in one solution, one would have to decide which traits are most desirable. In comparison to the HD800s it feels like you are giving up less with the HE-6s because of their more widely appealing qualities.

Moving on from the EF-1 headphone amplifier to the beastly Denon PMA-QS1 through the speaker tap adapter and the HE-6s reveal even more details across the line. The PMA-QS1 really helped to bring the bass to the next level of precision and brought it down a notch volume wise, making the HE-6s sound more balanced. One issue with the speaker adapter is that it does seem to add some amplification in the 2-3 kHz range making the headphones sound a bit more sibilant. On a good amplifier like the PMA-QS1 this is a minor issue, but compared to the price of the solution any performance hit should be avoided. The remedy to this is of course to buy a better headphone amplifier, but that is usually a very expensive solution.

Since the Head-Direct HiFiMAN HE-6s cost $1,199 it is fair to assume that the end user will have a decent amplifier to power them. Head-Direct recommends their EF-5 amplifier which has a good reputation just like that of the EF-1, however, a more elaborate design will be able to bring them closer to their true potential, which is collosal.