Sennheiser HD 660S2 Review
Making good things better without letting the price explode. That was the task when it came to developing the brand-new open, dynamic headphone Sennheiser HD 660S2.
by Michael Lang
The Lower Saxony-based, family-owned company Sennheiser sold its soundbar and headphone division to the Swiss hearing aid specialist Sonova in 2021 and has since focused on microphones and studio technology, while the new owners are gradually working on modernizing and improving the product range in the fiercely competitive high-quality headphone market.
In doing so, they remain true to the dynamic principle in transducers, even though magnetostatic headphones have certainly established themselves in this price range in recent years and have earned a good reputation.
In terms of sound, magnetostatic headphones, which use strong magnets to vibrate a membrane, are certainly a serious alternative, but they have to contend with two disadvantages: The magnets used add a considerable amount of additional weight, which can negatively affect wearing comfort, and most magnetostats are not suitable partners for simple headphone jacks built into devices or even for mobile devices.
The main task for the HD 660S2 was primarily to give it a stronger foundation in the very lowest frequency ranges to impart even more body and tangibility to the sound, without losing the fundamental qualities of its predecessor, which was convincingly tested.
- 7Review earns Amazon affiliate commissions from qualifying purchases.
Among other things, the voice coil design was revised and the impedance increased to 300 ohms, as was already the case with the HD 600 and HD 650. According to Sennheiser, this new aluminum voice coil increases the magnetic field strength and is supposed to provide further improved impulse control, i.e., less distortion and thus a cleaner, more natural sound image.
Changes were also made to the housing; in particular, the airflow conditions were addressed and adjusted so that resonances occurring due to airflow in the housing are now better damped. The consequence is an improved impulse response across the entire frequency spectrum. All in all, all the aforementioned factors, including the doubling of sound pressure at the lowest frequencies, contribute to maximum precision, speed, and highest resolution in playback, if one follows the developers’ explanations.
WE LISTENED WITH
Cameo: WordUp
Sonny Rollins: Saxophone Colossus
High Wearing Comfort
A very important point with headphones, which we cannot emphasize often and intensely enough, is the wearing comfort and fit. Because the best-sounding headphone will spend most of its time unused in the shadows if it is uncomfortable to wear. Here, with the HD 660S2, you can feel the manufacturer’s many years of experience in achieving the ideal mixture of contact pressure and lasting comfort for almost every head shape and size as well as any anatomy of your ears. Thanks to the low weight of only 260 grams and the large, soft ear pads with velour covers, the 660S2 is very comfortable to wear even after hours and even for glasses wearers.
In addition to its lightness, its open design also helps, allowing you to listen to an entire opera without fatigue and without heat buildup. In the sum of its characteristics, it has an edge over most of its competitors, quite independent of its sonic merits, which we will come to shortly. And if you belong to the category of music lovers who like to nod their head back and forth while listening—by all means, the Sennheiser will remain calmly in the chosen original position on your head even then.
Also pleasing and worth mentioning are the replaceable cables and ear pads, while the search for the left and right ear cups once again requires detective efforts. A little tip: On the left side, there are three visible and tactile dots on the bracket!
If you are wondering how Sennheiser manages to deliver such a lightweight, high-quality headphone: The low, comfortable weight is also achieved through the generous use of plastic in the company’s own factory in Ireland. There, it is also ensured that one headphone sounds like the other, as the chassis are manufactured with minimal tolerances and their consistent quality is randomly checked.
TEST EQUIPMENT
Turntables: Oracle Delphi IV, Yamaha PX-2
CD Players: Sony SACD 777, Wadia 8/Brinkmann Nyquist 2
Phono Preamplifier: Audionet PAM G2
Headphone Amplifier: Lehmannaudio Linear SE
Headphones: Sennheiser HD 650, Sennheiser HD 660, Sendy Audio Apollo
Complementing the Sound Image
As a result, the HD 660S2 leaves nothing to be desired in terms of sound aspects. Fortunately, the development department resisted the temptation to turn a very good headphone in the $500 class into a populist bass monster in the $600 class. With numerous pieces of music, you only hear a slight tonal difference between old and new. Only when a recording is really well done do you notice the additional punch in the lowest frequencies and at the same time a somewhat finer, tidier reproduction with fewer artifacts, which also appears significantly more airy.
A first example of the gentle yet pleasing sonic revision was discovered when we listened to a string quartet by Giuseppe Verdi. The S2 sounded, in direct comparison to its predecessor and in relation to the HD 650, also in the $500 price class, more open, airy, and spacious. Despite more warmth in the sound image, it was always a touch more precise and cleaner, as became clear with Johnny Cash’s “Personal Jesus.” Similarly, when we switched from classical to jazz and funk sectors. When Stanley Clarke started “School Days,” it always sounded a touch warmer, but drier and remarkably more dynamic.
A very similar picture emerged when we devoted ourselves to other virtuosos like Marcus Miller or Ray Brown on double bass or Sonny Rollins on saxophone: The HD 660S2 never played itself spectacularly into the foreground but convinced due to its less anemic reproduction not only with basses and individual instruments or small ensembles but also with orchestral music like Mahler’s 4th Symphony. Surprisingly, however, crashing pop songs from Yello (“Rhythm Divine”) to Cameo (“WordUp”) let the differences melt away to an almost negligible degree.
Sennheiser HD 660S2 Specs
Warranty: 2 years
www.sennheiser-hearing.com
The successor to the bestseller HD 660S has been made comprehensively better than its successful predecessor through some modified details. Due to the overall more powerful yet even tighter bass reproduction, the sound image appears fuller and more natural without becoming bloated. Undoubtedly, sensitive experts were at work.
Lab Comment
300 Ohm impedance, weight 260 grams, sensitivity 104 dB—for mobile devices not a perfect partner, but most headphone amplifiers will be able to drive the Sennheiser without any problems. For best sound, however, a high-quality headphone amplifier should be used.
Features
Replaceable cables and ear pads, 1.8-meter cable with 6.3 mm jack and Pentaconn; 3.5 mm jack adapter included, transport pouch
Verdict
When you purchase through links on our site, I may earn an affiliate commission. Here’s how it works.
Is Sennheiser's new headphone REALLY an upgrade?
Sennheiser has produced a number of legendary headphones like the HD 580, HD 650, HD 600 and more. Now they've come out ...
Sennheisers HD 620S Review
Founded in July 2014, 7Review is a free audio resource for beginners, and we're dedicated to helping you create the ultimate movie-watching experience right at home. We pull insights from top audio magazines and trusted industry sources to bring you well-researched, reliable reviews and tips. Whether you're a home cinema pro or just starting out, we aim to give you the info you need to make the best choices for your setup.
