Description
The Sennheiser HD 660S 2 headphones take the performance of its predecessors, the HD 650 and HD 600, to the next level with its supernatural speed and effortless instrument reproduction, even to the ends of the frequency range. The natural, warm sound and extended sub-bass make it an ideal choice for audiophiles.
Enjoy the Sennheiser Sound
By using a brand-new transducer and a specially ventilated driver unit, the Sennheiser HD 660S 2 headphones are able to provide audiophiles with a sound that’s perfectly suited for reproducing complex and intricate recordings with confidence. It’s sharp, and detailed and maintains the engaging and dynamic qualities that make music enjoyable. The 38mm diaphragm is agile thanks to the aluminium voice coil, allowing for precise tonal and spatial characteristics to be communicated through ultra-quick fidelity.Meshes with Your Music
The HD 660S 2 has a steel mesh that’s impressive in design and performance. It completes the ventilated driver, which controls the air displacement consistently to minimise turbulence. Consequently, the diaphragm moves freely, allowing the music to be heard in its purest form, with a perfect balance of authenticity and expression. The steel composition enables much tighter production tolerances, resulting in consistent characteristics of every headphone produced. When combined with the open-back earcups, the sound produced by each transducer is unrestricted, mimicking the natural soundstage.Matched for Perfection
Each unit of the Sennheiser HD 660S 2 has undergone a matching process to pair the transducer with its counterpart on the opposite channel. These processes have very precise tolerances, and when combined with automated assembly, they ensure top-notch quality throughout.
Designed For Durability & Acoustics
The materials used to design the HD 660S 2 are lightweight and carefully chosen to not affect the acoustics of the system, while still maintaining the durability needed for daily, extended use.Connect to Any Source
The HD 660S 2 comes with multiple 9.8 feet /3m-long cables in the box. The ¼-inch / 6.3mm stereo connector is the standard plug for audiophiles and can be used with various devices such as headphone amplifiers, A/V receivers, digital audio players, and more. The 4.4mm balanced connector is designed for newer balanced output devices such as headphone amplifiers and digital audio players and provides a more stable connection over time.Transducer principle: dynamic, open
Transducer size: 38 mm
Frequency response: 8 – 41,500 Hz
Impedance: 300 Ω
Sound pressure level (SPL): 104 dB (1 kHz, 1 Vrms)
Total harmonic distortion (THD): <0.04% (1 kHz, 100 dB)
Ear coupling: Over-Ear
Weight: 260g
Adapter: 6.3 mm (1⁄4 inch) to 3.5 mm
Connector: 6.3 mm (1⁄4 inch) jack plug, 4.4 mm balanced plug
Cable length: 1.8m
Country of origin: Ireland
Magnetic field: 4.5mT
What's included
HD 660S2 headphones
6.3 mm cable (1.8 m), 4.4 mm cable (1.8 m)
6.3mm to 3.5mm adapter
Carry pouch
Warranty Period: 2 Years from the date of Invoice
Covered: Manufacturing Defects Only
Website: https://en-in.sennheiser.com/service-support-contact-service-centers-in-india
Contact No: 1800 22 36 32
Email Id: in-info@sennheiser.com
Sennheiser is a well-known brand in the audio industry. They offer a wide range of products catering to both audiophiles and casual listeners. Their products include open back and closed back audiophile headphones, in-ear monitors, ANC headphones, and true wireless earbuds. They are known for their exceptional sound quality and durability. Whether you're a professional musician or just a music enthusiast, Sennheiser has something for everyone.
H660S2 is very well built transducer, it's quite clampy out of the box. The clamps can be eased but stretch softly over the metal band on both side.
Sound: music is warm with mids forward. Spiciness in the treble is not noticed. Bass is also subdued.
Note: My previous headphone are 560s, Sundara, Eligia and Clears.
Comparison:
With 560s: the 560s is v shaped compared to 660s2. Mids/vocals sound so good on 660s2. But the sub bass, mid bass, highs sound bit better on 560s. 660s2 suits clasical music while 560s suits rock, electronic and pop music. 560s also tend to distort with volume and eq, 660s2 doesn't sweat with volume and eq.
With focal clear: the focal clear is best in all genre no competition but vocals are slightly prefered on 660s2
With Sundara: Sundara sound very thin when compared but excels in details and soundstage.
Overall 660S2 or any of the 6X0 series headset are must for audiophiles. This headset sings with right vocal based tracks.

Sounds very enjoyable and open and also has good imaging and instrument separation and definition to the various components of music is great. More clarity than HD 650 and also warmer but crispy sounding. I have the ifi zen stack but I like it more with just the zen dac v2 balanced output. Great headphone under 30k if you like warm sound with vocal intimacy and details of instruments.
You will enjoy the music as these sound good but little tight fit heavy when compared to competition like Sony MDR MV1 (which I owned already) . It's good looking when we compare it to Sony ones but only problem for me is it's tight fitting and I found little heavy for long listening, I can't bear these or even sony more then 40 mintues max in one go. Price could also be little better. But it's worthy one if you want to enjoy music at its best at stage live performance rather then in your head like closed back. One of the best ones in open back but again little tight fit and heavy for me.
Thank you for your review of the Sennheiser HD 660S2 Open Back Headphones. We appreciate your feedback and are glad to hear that you are enjoying the sound quality. We apologize for any discomfort caused by the tight fit and weight of the headphones. Thank you for choosing Sennheiser, The Audio Store and happy listening!

Description
The Sennheiser HD 660S 2 headphones take the performance of its predecessors, the HD 650 and HD 600, to the next level with its supernatural speed and effortless instrument reproduction, even to the ends of the frequency range. The natural, warm sound and extended sub-bass make it an ideal choice for audiophiles.
Enjoy the Sennheiser Sound
By using a brand-new transducer and a specially ventilated driver unit, the Sennheiser HD 660S 2 headphones are able to provide audiophiles with a sound that’s perfectly suited for reproducing complex and intricate recordings with confidence. It’s sharp, and detailed and maintains the engaging and dynamic qualities that make music enjoyable. The 38mm diaphragm is agile thanks to the aluminium voice coil, allowing for precise tonal and spatial characteristics to be communicated through ultra-quick fidelity.Meshes with Your Music
The HD 660S 2 has a steel mesh that’s impressive in design and performance. It completes the ventilated driver, which controls the air displacement consistently to minimise turbulence. Consequently, the diaphragm moves freely, allowing the music to be heard in its purest form, with a perfect balance of authenticity and expression. The steel composition enables much tighter production tolerances, resulting in consistent characteristics of every headphone produced. When combined with the open-back earcups, the sound produced by each transducer is unrestricted, mimicking the natural soundstage.Matched for Perfection
Each unit of the Sennheiser HD 660S 2 has undergone a matching process to pair the transducer with its counterpart on the opposite channel. These processes have very precise tolerances, and when combined with automated assembly, they ensure top-notch quality throughout.
Designed For Durability & Acoustics
The materials used to design the HD 660S 2 are lightweight and carefully chosen to not affect the acoustics of the system, while still maintaining the durability needed for daily, extended use.Connect to Any Source
The HD 660S 2 comes with multiple 9.8 feet /3m-long cables in the box. The ¼-inch / 6.3mm stereo connector is the standard plug for audiophiles and can be used with various devices such as headphone amplifiers, A/V receivers, digital audio players, and more. The 4.4mm balanced connector is designed for newer balanced output devices such as headphone amplifiers and digital audio players and provides a more stable connection over time.Transducer principle: dynamic, open
Transducer size: 38 mm
Frequency response: 8 – 41,500 Hz
Impedance: 300 Ω
Sound pressure level (SPL): 104 dB (1 kHz, 1 Vrms)
Total harmonic distortion (THD): <0.04% (1 kHz, 100 dB)
Ear coupling: Over-Ear
Weight: 260g
Adapter: 6.3 mm (1⁄4 inch) to 3.5 mm
Connector: 6.3 mm (1⁄4 inch) jack plug, 4.4 mm balanced plug
Cable length: 1.8m
Country of origin: Ireland
Magnetic field: 4.5mT
What's included
HD 660S2 headphones
6.3 mm cable (1.8 m), 4.4 mm cable (1.8 m)
6.3mm to 3.5mm adapter
Carry pouch
Warranty Period: 2 Years from the date of Invoice
Covered: Manufacturing Defects Only
Website: https://en-in.sennheiser.com/service-support-contact-service-centers-in-india
Contact No: 1800 22 36 32
Email Id: in-info@sennheiser.com
Sennheiser is a well-known brand in the audio industry. They offer a wide range of products catering to both audiophiles and casual listeners. Their products include open back and closed back audiophile headphones, in-ear monitors, ANC headphones, and true wireless earbuds. They are known for their exceptional sound quality and durability. Whether you're a professional musician or just a music enthusiast, Sennheiser has something for everyone.
H660S2 is very well built transducer, it's quite clampy out of the box. The clamps can be eased but stretch softly over the metal band on both side.
Sound: music is warm with mids forward. Spiciness in the treble is not noticed. Bass is also subdued.
Note: My previous headphone are 560s, Sundara, Eligia and Clears.
Comparison:
With 560s: the 560s is v shaped compared to 660s2. Mids/vocals sound so good on 660s2. But the sub bass, mid bass, highs sound bit better on 560s. 660s2 suits clasical music while 560s suits rock, electronic and pop music. 560s also tend to distort with volume and eq, 660s2 doesn't sweat with volume and eq.
With focal clear: the focal clear is best in all genre no competition but vocals are slightly prefered on 660s2
With Sundara: Sundara sound very thin when compared but excels in details and soundstage.
Overall 660S2 or any of the 6X0 series headset are must for audiophiles. This headset sings with right vocal based tracks.

Sounds very enjoyable and open and also has good imaging and instrument separation and definition to the various components of music is great. More clarity than HD 650 and also warmer but crispy sounding. I have the ifi zen stack but I like it more with just the zen dac v2 balanced output. Great headphone under 30k if you like warm sound with vocal intimacy and details of instruments.
You will enjoy the music as these sound good but little tight fit heavy when compared to competition like Sony MDR MV1 (which I owned already) . It's good looking when we compare it to Sony ones but only problem for me is it's tight fitting and I found little heavy for long listening, I can't bear these or even sony more then 40 mintues max in one go. Price could also be little better. But it's worthy one if you want to enjoy music at its best at stage live performance rather then in your head like closed back. One of the best ones in open back but again little tight fit and heavy for me.
Thank you for your review of the Sennheiser HD 660S2 Open Back Headphones. We appreciate your feedback and are glad to hear that you are enjoying the sound quality. We apologize for any discomfort caused by the tight fit and weight of the headphones. Thank you for choosing Sennheiser, The Audio Store and happy listening!
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from 5552 reviews
Kudos to makers/seller for making it to available.
Purest form of audio hearing experience with this cable.
Happy with the purchase.

The build quality of this cable is top-notch. I’m using it with my HD560S connected to a laptop via Apple Music, and the difference is noticeable. The bass feels tighter and especially welcome improvement for openback headphones and there's a clear boost in instrument separation and overall clarity. Upgrading to a balanced connection has definitely proven to be a worth while decision.

The Hisenior Mega5EST is a reference-quality IEM tuned with taste and subtlety. It doesn't shout for attention but rather invites you to listen deeper. If you're looking for an IEM that balances technical excellence with musical emotion, this one is a rare gem in the hybrid space. A true “listen for hours, forget the gear” experience.

This is the best MP3 player you can get for this price.

I'm new to the world of IEMs and this one was bought to try how it feels. Trust me, it won't disappoint you. Double the value compared to headphones of the same rate.

Budget king SMSL RAW MDA1. Very versatile music dac & headphone amp. Fully satisfied. Being an audiophile I was searching for best budget one got this from The audio store. Thanks for timely delivery. Nothing can match it at this price range period.

Works well with my Moto Edge 50 Pro. Other DAC's would have a lot of interference and static, the Moondrop Echo A has none. Audio is clear and the connector does not heat up at all. Battery life isn't impacted as well.
The build quality is excellent, cable is flexible and will fit in any iem carry case as well.

This is a great product with excellent sound quality. The bass is impressive and it's worth the money.

Beautiful and heavy duty balanced cable. Adds a weight to the music's bass i.e. tighter bass response.
Good product excellent sound well packed but delivery was delayed by two days.otherwise everything good.

Combo of cx31993 max97220 chip is more than sufficient to drive any iems

Using it with truthear crinicle zero red and works perfectly. Loving it

I’ve been thoroughly impressed with the SMSL RAW MDA-1, especially as someone who values Hi-Res audio and the transformative power of a great DAC+amplifier.
The build is solid, with a sleek, compact design that fits perfectly on my desk without taking up too much space. I love the variety of connectivity options—USB-C, coaxial, optical, and Bluetooth—making it easy to connect to my PC, gaming console, or even my phone. The Bluetooth feature is particularly handy for wireless listening when I want to move around without sacrificing sound quality.
One thing I’ve found is that it’s exceptionally well-suited for low to medium impedance headphones, delivering plenty of power and clarity. However, if you’re using high-impedance headphones, you might notice it struggles a bit with volume, so you may need an external amplifier for those. Also, while the 4.4mm headphone output is convenient, it’s not a true balanced design, which might be a letdown for audiophiles who prioritize that feature.
Given its price point, the SMSL RAW MDA-1 offers exceptional value, delivering high-end features and performance that punch above its weight class. It is particularly suitable for audiophiles and gamers seeking a high-quality desktop audio solution with both wired and wireless options. However, for those with high-impedance headphones or a preference for advanced sound-shaping features, it may fall short, potentially requiring supplementary equipment.

KZ Castor Harman Target with Improved Bass is just bliss for listening to music & watching movies.
I play lots of pc games, this IEMs are just awesome for gaming.. The sound stage is fantastic 🔥🔥. Loved using it for movies & games ❤️🔥🤩

It's simply wow
I discovered new things in my favorite audio.
That's how good it is.
5/5