Sennheiser HD 660S2 Review 2026: Audiophile Headphone Worth It?

Are you looking for an open back headphone that delivers studio grade sound without breaking the bank? The Sennheiser HD 660S2 has been on audiophile radar since its 2023 launch. It promises deep sub bass, natural mids, and a relaxed treble. But in 2026, does it still hold up against newer competition?

I spent weeks testing this headphone across music genres, gaming sessions, and podcast listening. The results surprised me. This review covers everything from build quality and comfort to sound signature and value. Whether you are an audiophile veteran or a curious newcomer, this breakdown will help you decide if the HD 660S2 deserves a spot on your desk.

Stick around. By the end of this review, you will know exactly whether this headphone fits your needs, your ears, and your budget.

Key Takeaways

• The Sennheiser HD 660S2 uses a 38mm dynamic driver with an ultra light aluminum voice coil. It delivers a frequency response of 8 Hz to 41,500 Hz, which covers deep sub bass to airy highs with ease.
• Bass is the biggest upgrade over the original HD 660S. The HD 660S2 extends lower and hits harder while keeping the midrange clean and free from bleed. Bass lovers in the Sennheiser 600 series family will appreciate this change.
• The 300 ohm impedance means you need a decent amplifier to drive these headphones properly. A phone or laptop alone will not give you the full experience. Pair them with a dedicated headphone amp or DAC/amp combo for best results.
• Comfort remains excellent for long listening sessions. The velour ear pads and lightweight 260 gram frame let you wear them for hours without fatigue. The clamping force is firm out of the box but loosens over time.
• The retail price sits around $499, but frequent discounts bring it down to the $380 to $420 range in 2026. At the discounted price, this headphone offers strong value for its performance tier.
• Competition has grown stronger since launch. Headphones like the Beyerdynamic DT 900 Pro X and HiFiMAN Sundara offer different strengths at similar or lower price points. Your preference for sound signature will guide your final pick.

Sennheiser HD 660S2 Overview and First Impressions

The Sennheiser HD 660S2 arrived in early 2023 as the successor to the popular HD 660S. It belongs to the legendary Sennheiser 600 series family that includes the HD 600, HD 650, and HD 6XX. This lineup has earned respect from audiophiles and music professionals for over two decades.

Right out of the box, the HD 660S2 looks and feels familiar. Sennheiser kept the classic open back design with an oval ear cup shape. The matte black finish gives it a clean, understated aesthetic. There is no flashy branding or RGB lighting here. This headphone is all about the sound.

The packaging includes two cables. You get a 6.35mm terminated cable and a 4.4mm balanced cable. The balanced cable is a welcome addition that many competitors skip at this price point. Both cables measure 1.8 meters in length and feel sturdy without being overly stiff.

First impressions on the head are positive. The ear pads surround your ears fully. The headband distributes weight evenly across the top of your head. I noticed the clamping force was firm during the first few hours, but this relaxed after a couple of days of regular use.

Build Quality and Design

The HD 660S2 follows a proven design philosophy. Sennheiser did not reinvent the wheel here. The headband uses a mix of metal and reinforced plastic. This combination keeps weight low while maintaining durability.

The ear cups attach to the headband with a reliable click mechanism. They swivel slightly to adjust to different head shapes. The open back grilles on each ear cup feature a distinctive pattern. This open design lets air flow through the drivers, which creates that spacious sound staging open back headphones are known for.

Build quality feels solid but not premium. If you are coming from a headphone with metal construction throughout, the plastic parts may feel less impressive. However, Sennheiser has proven this design can last for years. Replacement parts are easy to find, including ear pads, cables, and headband padding.

The detachable cable system uses a proprietary two pin connector at the headphone end. This is different from the standard 3.5mm or MMCX connectors. You will need Sennheiser compatible cables if you want aftermarket options. This limits your choices compared to headphones with universal connector systems.

Overall, the build quality matches what you expect from Sennheiser at this price point. It is reliable, repairable, and functional.

Comfort and Fit

Comfort is one of the strongest selling points of the HD 660S2. At just 260 grams, this is one of the lightest audiophile desktop headphones available. You can wear it for four to six hour sessions without feeling pressure or heat buildup.

The velour ear pads feel soft against your skin. They breathe well because of the open back design. This prevents the sweaty ear feeling that closed back headphones often cause. The oval shape of the ear cups fits most ear sizes comfortably.

The headband padding is thin but adequate. It sits gently on the top of your head. Some users with larger heads may feel pressure at the crown after extended use. If this happens, you can bend the metal headband outward slightly to reduce clamping force.

Clamping force is moderate to firm out of the box. This is consistent with other Sennheiser 600 series headphones. The upside of this clamp is a secure fit that keeps the drivers properly positioned over your ears. This matters for sound quality because driver placement affects imaging and frequency response.

Glasses wearers should note that the velour pads accommodate thin to medium frames well. Thick glasses arms may create a slight gap that affects the bass seal. This is a common issue with most open back headphones, not unique to the HD 660S2.

Sound Quality: Bass Performance

The bass is where the HD 660S2 separates itself from its predecessor. Sennheiser redesigned the airflow transducer and vented magnet system to deliver deeper sub bass extension. The result is noticeable.

Sub bass reaches down to the rated 8 Hz, and you can feel rumble in tracks that demand it. Electronic music, hip hop, and orchestral pieces with deep bass notes benefit from this extension. The HD 660S2 does not sound bass heavy. Instead, it sounds complete. The low end fills in the gap that the original HD 660S left open.

Mid bass is clean and controlled. Kick drums have punch without bloating into the lower midrange. Bass guitar lines remain distinct and textured. You can hear individual notes rather than a muddy blob of low frequency sound.

Compared to the HD 650, the HD 660S2 offers tighter bass with better definition. The HD 650 has a warmer, looser low end that some listeners prefer for genres like jazz and acoustic music. The HD 660S2 bass works better for modern genres that rely on clean, impactful low end.

If you want headphone bass that slams like a subwoofer, this is not the right pick. The HD 660S2 delivers audiophile bass: accurate, extended, and well controlled. It satisfies without overwhelming.

Top 3 Alternatives for Sennheiser HD 660S2

If the HD 660S2 does not perfectly match your needs, these three headphones offer excellent alternatives at similar price points. Each brings a different sound signature and feature set to the table.

1. Sennheiser HD 600

The HD 600 is the classic reference headphone. It has a brighter treble and a more neutral midrange compared to the HD 660S2. If you prioritize vocal clarity and treble detail, the HD 600 is a strong choice. It costs significantly less than the HD 660S2, which makes it an excellent value pick. The trade off is less sub bass extension and an older design.

2. Beyerdynamic DT 900 Pro X

The DT 900 Pro X offers a wider soundstage and easier drivability at 48 ohms. You can plug it into a laptop or phone and get respectable volume. The sound signature is brighter and more analytical than the HD 660S2. This makes it a great option for mixing, mastering, and critical listening. Build quality is also excellent with a spring steel headband.

3. HiFiMAN Sundara

The Sundara uses planar magnetic drivers instead of dynamic drivers. This gives it faster transient response and a different texture to the sound. Bass is tight and precise. The soundstage is wider than the HD 660S2. The Sundara trades some of the Sennheiser’s midrange warmth for greater technical precision. It is a top pick for listeners who want speed and detail.

Sound Quality: Midrange Performance

The midrange has always been the crown jewel of Sennheiser’s 600 series. The HD 660S2 carries this tradition forward. Vocals sound natural, present, and emotionally engaging. Male and female vocals sit forward in the mix without sounding aggressive.

Acoustic instruments benefit greatly from this midrange presentation. Guitars have body and texture. Piano notes ring with accurate decay. String instruments like violin and cello sound rich and full. The midrange does not color the sound too much. It stays true to the recording.

The upper midrange has a slight lift that adds presence to vocals and lead instruments. This prevents the sound from feeling recessed or distant. Some listeners may find the HD 660S2 slightly forward in this region compared to the more laid back HD 650. This is a matter of personal taste.

One area where the midrange excels is instrument separation. Even in dense mixes with multiple instruments, the HD 660S2 keeps each element distinct. You can pick out individual layers in a full band recording without straining. This makes it a pleasure for critical listening sessions where detail matters.

Sound Quality: Treble Performance

Treble on the HD 660S2 takes a relaxed approach. Sennheiser tuned the high frequencies to avoid harshness and sibilance. This makes it a fatigue free headphone for long listening sessions.

The treble extends well up to the rated 41,500 Hz. Cymbals shimmer with natural decay. Hi hats have crisp articulation without sounding thin or metallic. The air and sparkle in the top end add a sense of openness to the sound.

There is a slight dip around the 5 kHz range. This reduces the perception of sharpness in consonants and vocal sibilance. Some listeners call this a “smooth” or “relaxed” treble. Others may feel it lacks energy and excitement compared to brighter headphones like the HD 600 or Beyerdynamic DT 900 Pro X.

A small peak around 9 kHz adds a touch of brightness. This prevents the treble from sounding completely dark or veiled. The balance works well for most genres. Rock, pop, classical, and electronic music all sound pleasant without the treble calling attention to itself.

If you are sensitive to bright or harsh treble, the HD 660S2 is a safe choice. If you prefer treble that sizzles and sparkles aggressively, you may want to look elsewhere.

Soundstage and Imaging

Open back headphones are known for their soundstage advantage. The HD 660S2 delivers a moderate soundstage that feels natural and intimate. Instruments occupy defined positions around your head rather than sounding like they come from inside your skull.

Width is decent but not expansive. The HD 660S2 sounds like you are sitting in a small to medium sized room. It does not recreate the wide, arena like presentation that headphones like the HD 800S or HiFiMAN Arya deliver. This is expected at this price point.

Imaging is a strong suit. Left to right positioning is precise. You can point to where each instrument sits in the stereo field. This makes the HD 660S2 a solid choice for gaming as well. Footsteps and environmental cues in games have clear directional placement.

Depth is moderate. The HD 660S2 places some instruments forward and others slightly behind. This front to back layering adds realism to the listening experience. However, it does not match the three dimensional depth that higher priced headphones achieve.

For its price range, the soundstage and imaging performance is competitive. The intimate presentation works especially well for vocal centric music, podcasts, and acoustic recordings.

Amplification and Source Requirements

The HD 660S2 has a 300 ohm impedance and a sensitivity of 104 dB at 1 Vrms. These numbers mean it needs more power than typical consumer headphones to reach satisfying volume levels.

A smartphone or laptop headphone output will drive the HD 660S2 to listenable volume. But you will miss out on dynamics and bass impact. A dedicated headphone amplifier unlocks the full potential of these headphones. The difference is noticeable, especially in the low end and overall dynamic range.

Popular amp pairings include the Schiit Magni, JDS Labs Atom, and iFi Zen DAC. These affordable amplifiers provide enough power to drive the HD 660S2 with authority. You do not need to spend hundreds on amplification. A $100 to $200 amp will do the job well.

The included 4.4mm balanced cable opens the door to balanced amplification. Balanced output can provide slightly more power and lower noise floor. If your amp has a balanced output, use it. The improvement is subtle but real.

Tube amplifiers pair beautifully with the HD 660S2. The natural warmth of tubes complements the headphone’s smooth sound signature. This combination creates a lush, musical experience that many audiophiles enjoy.

Gaming and Movie Performance

While the HD 660S2 is marketed as a music headphone, it performs well for gaming and movies. The accurate imaging helps you locate sounds in competitive games. Footsteps, gunshots, and environmental cues have clear directional placement.

For single player games with rich soundtracks, the HD 660S2 shines. The warm midrange and extended bass bring cinematic audio to life. Explosion effects have satisfying rumble without drowning out dialogue or music.

Movie watching is enjoyable thanks to the natural vocal presentation. Dialogue stays clear and centered even during loud action scenes. The open back design does leak sound, so late night movie watching may disturb others nearby.

The HD 660S2 does not have a built in microphone. You will need a separate microphone for voice chat during online gaming. A desktop microphone or a modular boom mic attachment works well.

One limitation for gaming is the soundstage size. Competitive gamers who rely on wide sound positioning may prefer headphones with a larger soundstage. The HD 660S2’s intimate presentation works well for immersion but may not give you the widest positional audio.

Sennheiser HD 660S2 vs HD 650

This comparison comes up constantly because both headphones share DNA. The HD 650 is warmer and more laid back in its overall presentation. The HD 660S2 is cleaner, tighter, and more resolving.

Bass on the HD 650 is softer and has a gentle roll off in the sub bass. The HD 660S2 extends deeper and hits with more authority. If you listen to bass heavy genres, the HD 660S2 is the better pick. For jazz, classical, and acoustic music, the HD 650’s warmth can sound more natural and inviting.

The midrange on both headphones is excellent. The HD 650 has a slightly thicker, richer midrange. The HD 660S2 has a cleaner midrange with better separation. Vocals sound beautiful on both, but the HD 660S2 reveals more micro detail.

Treble is smoother on the HD 650. The HD 660S2 has a bit more top end energy while still avoiding harshness. Detail retrieval is better on the HD 660S2 across the entire frequency range.

The HD 650 costs significantly less. In 2026, you can find it for around $250 to $300. The HD 660S2 sits at $400 to $500 depending on sales. Whether the improvement justifies the price difference depends on your sensitivity to these sonic differences and your budget.

Cable Options and Accessories

The HD 660S2 comes with a generous cable package. You get a 1.8 meter cable terminated with a 6.35mm (quarter inch) plug. You also get a 1.8 meter cable terminated with a 4.4mm Pentaconn balanced plug. A 6.35mm to 3.5mm adapter is included as well.

The balanced cable is a standout inclusion. Many headphones in this price range only include a single ended cable. Having a balanced option out of the box saves you from buying a separate cable.

The cables use a proprietary Sennheiser two pin connector at the headphone end. This connector locks securely into place. Third party cable options exist from companies like Hart Audio, NewFantasia, and Periapt. These aftermarket cables give you access to different terminations like 2.5mm balanced or XLR.

The included cables are adequate in quality. They are flexible enough to avoid being annoying on your desk. They do not tangle easily. However, they are not particularly premium feeling compared to aftermarket braided cables.

A carrying pouch or hard case is not included. You will need to purchase one separately if you plan to transport these headphones. This is a minor omission that many users won’t care about since the HD 660S2 is primarily a desktop headphone.

Who Should Buy the Sennheiser HD 660S2?

The HD 660S2 fits a specific type of listener. If you value natural, accurate sound with a touch of warmth, this headphone delivers. It rewards careful listening and reveals details in well recorded music.

Music lovers who enjoy vocals, acoustic instruments, and layered productions will get the most enjoyment from the HD 660S2. It handles every genre competently, but it truly excels with music that has strong vocal performances and instrumental texture.

Audiophile beginners looking for their first serious open back headphone should consider the HD 660S2. It provides a taste of high end sound without requiring extreme investment in amplification. A basic amp and the HD 660S2 create a satisfying starter setup.

Content creators who need accurate monitoring will appreciate the natural frequency response. Podcasters, vocalists, and musicians can trust what they hear through the HD 660S2.

This headphone is not ideal for listeners who want heavy bass impact, aggressive treble, or a massive soundstage. It is also not suitable for outdoor use due to its open back design and wired connection.

Pricing and Value in 2026

The Sennheiser HD 660S2 launched at $599.95 MSRP. That launch price drew criticism from many reviewers and consumers. The consensus was that $600 was steep for what the headphone offered over cheaper 600 series siblings.

In 2026, the market has corrected. Street prices regularly drop to the $380 to $420 range. Amazon, Best Buy, and other retailers frequently discount the HD 660S2 during sales events. At these prices, the value proposition improves significantly.

Compared to the competition, the HD 660S2 at around $400 makes strong sense. You get excellent build quality, a balanced cable, natural sound, and the reliability of the Sennheiser brand. Replacement parts ensure this headphone can last five to ten years with basic maintenance.

If you find it at or below $400, the HD 660S2 is a confident recommendation. At the full $500+ retail price, the value becomes harder to justify given alternatives like the HD 600 at $280 or the Sundara at a similar price point.

Watch for sales. The HD 660S2 goes on discount frequently. Patience can save you $100 to $200 off the retail price.

Final Verdict

The Sennheiser HD 660S2 remains a strong contender in the mid range audiophile headphone space in 2026. It delivers improved bass over its predecessor, a beautiful midrange, and a smooth treble. Build quality is reliable. Comfort is excellent. The included balanced cable adds genuine value.

It is not a perfect headphone. The soundstage could be wider. The clamping force runs firm. The proprietary cable connector limits aftermarket options. But these are minor complaints in the context of overall performance.

If you want a headphone that sounds natural, revealing, and musical all at once, the HD 660S2 earns its place on your shortlist. Grab it on sale, pair it with a decent amp, and enjoy hundreds of hours of listening pleasure.

Frequently Asked Questions

Is the Sennheiser HD 660S2 good for gaming?

Yes, the HD 660S2 works well for gaming thanks to its accurate imaging and clear sound. Competitive gamers can locate sounds precisely. The open back design creates a natural sense of space. However, headphones with wider soundstage may offer a slight edge in large map games.

Does the Sennheiser HD 660S2 need an amplifier?

The HD 660S2 has 300 ohm impedance. It benefits greatly from a dedicated headphone amplifier. While it can produce sound from a phone or laptop, an amp improves bass impact, dynamics, and overall volume. Budget amps like the Schiit Magni or JDS Labs Atom work well.

How does the HD 660S2 compare to the HD 600?

The HD 600 has a brighter treble and less sub bass extension. The HD 660S2 offers deeper bass, a slightly warmer top end, and better resolution. The HD 600 costs less and remains an excellent option. Your preference for bass or treble emphasis will guide your choice.

Is the Sennheiser HD 660S2 comfortable for long sessions?

Absolutely. The HD 660S2 weighs only 260 grams and uses breathable velour ear pads. Most users can wear it for four to six hours without discomfort. The clamping force is firm at first but loosens with use.

Can I use the Sennheiser HD 660S2 outdoors?

The HD 660S2 is an open back, wired headphone. It leaks sound outward and lets external noise in. It is best used in quiet indoor environments. It is not practical for commuting, gym use, or outdoor listening.

What is the best price to buy the HD 660S2 in 2026?

The MSRP is $499 to $599, but street prices often drop to $380 to $420 during sales. Check Amazon, Best Buy, and audio specialty retailers for the best deals. Buying during holiday sales or Prime Day events can save you the most money.

Last update on 2026-05-01 / Affiliate links / Images from Amazon Product Advertising API