Sennheiser HD 660 S Review | 93 Data compared

The Sennheiser HD 660 S updates the legendary 600 series with a darker, matte black and anthracite color scheme and a significantly reduced impedance of 150 Ohms, making it twice as easy to power as its predecessors. In the box, users receive the over-ear open-back headphones alongside a 1/4" (6.35mm) unbalanced cable, a 4.4mm balanced Pentaconn cable, and a 1/8" (3.5mm) adapter. Its build quality relies on a more durable-looking plastic than previous models, though the form-fitting design feels tight out of the box and requires extended wear to loosen. Sound-wise, the headphones feature matched drivers within a +/- 1dB tolerance and an expanded frequency range of 10Hz to 41kHz, which initially delivers a relatively flat, stiff response that opens up after proper burn-in time. The review highlights several prominent pros, including a highly detailed and "crisp" bass response that excellently captures the punch of bass guitars and synth lines, a pleasingly crisp midrange, and an ample soundstage courtesy of the open-back design. Furthermore, its lowered impedance allows it to remain tight and unflappable even at intense sound pressure levels,...

The Sennheiser HD 660 S over-ear headphone ($499) serves as a modern, portable-friendly update to the classic HD 650 model. It features a lower impedance of 150 ohms (reduced from 300 ohms), making it significantly easier to drive using portable digital audio players (DAPs) and entry-level gear without requiring expensive external amplification. In terms of sonic performance, the review highlights pros such as a sweet, smooth, and relaxing overall tonality, an excellent balanced midrange with lush vocals, and a well-engineered treble that offers a touch of sparkle without becoming sibilant or harsh. Additionally, it improves upon its predecessor with cleaner, crisper attack and decay properties, resulting in a tighter bass presentation that handles fast musical passages—like heavy metal kick drums—without getting sloppy. It also delivers an above-average open soundstage with impressive depth layering and pinpoint instrument imaging. Conversely, the review notes several cons that may deter traditional audiophiles who own high-end desktop rigs. Because of the lower impedance, the HD 660 S loses some overall scalability, leaving some transparency on the table and falling short of the grain-free, ultra-transparent presentation...

The Sennheiser HD 660 S are high-quality, open-back headphones praised for their neutral sound, exceptional mid-range accuracy, and comfortable, stable design suitable for long listening sessions. They are highly rated for wired gaming and deliver consistent frequency response, making them ideal for critical listening in quiet environments. RTINGS.comHowever, the review notes they lack low-bass extension for impactful audio and feature inconsistent treble that can sound dull or piercing. Their open-back design results in poor noise isolation and high audio leakage, while they also lack a built-in microphone for calls. RTINGS.

The SoundGuys review of the Sennheiser HD 660S highlights their durable, lightweight construction, comfortable fit for extended use, and a sound profile closely trailing the analytical tuning of the HD 600. Key pros include exceptional, detailed audio performance and robust, comfortable design suitable for critical listening. However, a key con is that the audio deviates slightly from the strict, hyper-analytical accuracy of the older HD 600 model, which may disappoint those seeking absolute clinical neutrality. As open-back headphones, they also lack noise isolation, making them unsuitable for loud or public environments.

The Sennheiser HD 660S are wired, open-back headphones launched in 2017 that remain an excellent audio choice. They feature a comfortable, lightweight 260g design made of smooth black plastic with an eye-catching stainless-steel outer grille. This model uses 42mm drivers with a 150-ohm impedance, making them easy to plug into portable devices like smartphones. Users will find great comfort in the soft cushioning on the headband and ears. The package also includes two long three-metre cables for different audio jacks. The main advantages of these headphones are their superb sound quality, lightweight body, and spacious soundstage. They handle complex tempos easily and deliver spectacular, lively mid-range tones. However, the review notes a few distinct drawbacks. The bass response lacks a strong punch for rock or metal music. They also lack wireless capabilities, and the frame cannot fold down, making them bulky to travel with.

The Sennheiser HD660S is an open-back headphone priced at $400 that maintains the visual identity and core design DNA of its predecessors, the HD600 and HD650. In terms of performance pros, the redesign successfully lowers the impedance by half compared to the HD650, reducing the dependency on high-voltage amplification and making it considerably more mobile-friendly and easier to drive with portable gear. Out-of-the-box sound quality is described as very good with a midrange-balanced presentation, clean channel matching, and less perceived "veil" than older models in the 6-series line. Furthermore, the headphones are noted for being highly comfortable, particularly due to their lightweight design when compared to heavier everyday alternatives. Conversely, the review highlights several distinct performance cons, notably a typical loss of deep bass response, a deficiency in the lower treble that hurts spatial qualities, a messy group delay, and an unusual peak resonance above 5 kHz. Because the stock frequency response is rougher than that of the HD650, the reviewer states that applying equalization (EQ) is mandatory to truly open up the fidelity and expand the soundstage. Additionally, community...

The Sennheiser HD 660 S provides a detailed, clean audio experience with a standout midrange and precise spatial imaging, suitable for both music and gaming. A notable improvement is the reduced 150-ohm impedance, which makes these headphones easier to drive, while the overall sound profile is versatile. However, the review highlights a significant lack of sub-bass extension. Furthermore, the headset is characterized by a high initial clamping force causing discomfort and an all-plastic construction that may not justify its price for some users.

Based on the provided review, the Sennheiser HD 660 S is a reimagined, open-backed over-ear headphone that modernizes the design DNA of its legendary predecessors, the HD 580, HD 600, and HD 650. Retailing at approximately £430, this model features an understated all-black aesthetic and is engineered to be less demanding of partnering amplification, allowing users to drive it directly from a phone or laptop. The reviewer notes that the HD 660 S is highly versatile across genres like electronic music, jazz, and noise rock because it introduces a warmer midrange and significantly more controlled bass depth than older models. Furthermore, its soundstaging is vastly improved, offering a much better stereo image that handles aggressive, noisy tracks comfortably without becoming overly harsh or tiring. However, the headphone does present specific drawbacks, particularly for listeners of classical or acoustic music. Its smooth, restrained upper registers tend to dull the sense of air, space, and fine ambient details—such as a musician breathing or turning score pages—pushing those elements too far into the background compared to older models like the HD 580 Precision....

The StereoNET review of the Sennheiser HD 660 S highlights the headphones as an exceptional evolutionary step in the HD 600 series, praising their technical refinement, forward midrange, and outstanding imaging. Key advantages include a clean, tightly driven bass response and a highly breathable open-back design that remains comfortable during long, private listening sessions. Conversely, the review notes that the, while clean, the bass lacks an earth-shattering sub-bass rumble or heavy physical impact. Additionally, the highly revealing, forward midrange can occasionally make certain tracks sound overly bright or "shouty," and the open-back design provides no isolation from external noise.

The Headfonia review characterizes the Sennheiser HD 660S as a versatile, open-back hybrid that balances the speed of the HD 600 with the musicality of the HD 650, featuring a 150-ohm impedance that makes it easy to drive via portable players. Key pros include excellent resolution, precise imaging, and enhanced performance when using the included 4.4mm balanced cable. Conversely, the review notes that the HD 660S suffers from rolled-off sub-bass, limiting performance on low-end heavy tracks, and its treble can be source-dependent. Additionally, it is noted to lack the distinct, iconic character of its predecessors, making it a stronger recommendation for newcomers rather than fans looking for a direct upgrade.

The Sennheiser HD 660 S represents an evolution of the iconic HD 580 and HD 650 lineage, introducing a re-engineered in-house transducer design, aluminum voice coils, and a precision stainless steel fabric diaphragm contour. Weighing 260g with elliptical ear cups, these open-backed headphones provide a firm yet comfortable grip. A significant technical upgrade is their lower 150 Ohm impedance, which makes them notably easier to drive than their predecessors, performing remarkably well even when paired with integrated amplifier systems rather than requiring expensive, specialist outboard gear. The package is also highly versatile, supplying a robust selection of oxygen-free copper cables with 6.35mm and 4.4 Pentaconn connectors alongside a 3.5mm adapter. Reviewer Paul Rigby awards the headphones an 8/10 rating, praising their insightful midrange, impactful bass, broad soundstage, and comfort, while explicitly noting there were no negative traits. The sonics are characterized by an airy, clean, and spacious soundstage that allows multi-instrument orchestral arrangements to expand with real depth rather than sounding muddy or clustered in the center. Midrange frequencies deliver exceptional detail and perception without introducing harshness or brightness, ensuring...

The Sennheiser HD 660sGo review by Gavin Fabiani-Laymond highlights these open-back headphones as an investment-worthy successor to the legendary HD 650, sharing an identical physical footprint that allows for interchangeable parts. A major pro is the drop in impedance to 150 ohms (with 104dB sensitivity), making them much easier to power from portable equipment like the LG V30 than their 300-ohm predecessors. Performance-wise, the audio features an incredibly detailed presentation, a massive soundstage with precise positioning, quick speed, and accurate, balanced bass. However, the headphones suffer from a few notable cons regarding design and utility. The large physical size creates a reasonable clamping force that can cause initial discomfort for some users, requiring a gentle stretch of the headband to resolve. Additionally, despite the lower impedance, they still require "beefy" amplification to achieve peak performance. Finally, their open-back construction causes significant sound leakage, meaning you will hear ambient background noise and anyone nearby will hear your music.

The Sennheiser HD 660 S, reviewed on Stereophile, offers a modernized design with a 150-ohm impedance that makes it efficient for portable use, providing a forward, impactful sound that reduces the traditional "Sennheiser veil". The headphones include comfortable, thick ear pads and a 4.4mm balanced cable, representing a more versatile, lightweight, and stealthy update to the classic 600-series, particularly in the lower-midrange presentation. Conversely, the review notes a lean, less warm sound profile with a bass roll-off below 100Hz, lacking the, richness of the HD 650. Sonically, the treble is described as grainier and edgier, failing to match the smooth refinement of its predecessors, while the out-of-the-box clamp force is notably high. Consequently, the review suggests the HD 600 remains a superior choice for sound quality.

Sennheiser HD 660 S community reviews highlight an open-back design with a lower 150-ohm impedance, making it easier to drive via portable gear. Strengths include exceptional resolution, intimate vocals, a smooth treble, and high comfort, though users note a significant sub-bass roll-off and an intimate, narrow soundstage. Reviewers also mention a high initial headband clamping force that requires break-in and often question the high price-to-performance ratio compared to similar models.