Sennheiser HD 660S2 Open-Back Headphones

In just one listen you will understand why the HD 660S is so special. Thousands of listening sessions later its purpose is even clearer. What you hear each and every time is the result of an open-back earcup mated to a new transducer tuned for the modern audiophile. Its speedy response is perfectly suited for reproducing those frequency-stretching recordings with confidence. Thanks to an aluminium voice coil, the 38mm diaphragm remains nimble for ultra-quick impulse fidelity across the board. This activation and rest behaviour unlocks the capability to communicate tonal and spatial characteristics precisely.

The steel mesh found on the HD 660S drive unit is interesting in design but most impressive when it comes to performance.

It completes the ventilated driver, offering consistent control of air displacement to reduce turbulence. As a result, diaphragm travel is pure, letting the music—and only the music—shine in a perfect balance of integrity and expression. The steel composition allows for much tighter production tolerances, ultimately contributing to remarkably consistent characteristics of each HD 660S produced. When combined with the open-back earcups, the sound emanating from each transducer is completely free to expand, just as it would in nature.

Today’s audiophile has more component choices than ever.

We optimised the HD 660S for efficiency on a wider range of devices to accommodate the varying levels of power present in output amplification circuitry. At 150 ohms, the HD 660S is the perfect partner for dedicated amplifiers, A/V receivers, and digital audio players (DAPs)—the magnet is more powerful than its predecessors, and thus easier to drive regardless of how your setup changes over time.

Every HD 660S has experienced a matching regimen to mate each transducer to its opposite-channel counterpart.

These tolerances are extremely narrow and when bolstered by automated assembly processes, ensure that your HD 660S experience is consistent with those all over the globe. We designed it with thoughtful, lightweight materials invisible to the acoustical system without sacrificing the durability needed for daily, all-day use. With a never-ending supply of music to consume, we wanted every touch point to be soft, luxurious, and durable for those extended listening sessions.

We packed your HD 660S with a versatile set of essential cables, each one impedance-matched with ultra-low capacitance.

The ¼-inch / 6.3mm stereo connector offers the audiophile-standard plug for connection to devices such as headphone amplifiers and A/V receivers, digital audio players, analogue gear, and more. A balanced, 4.4mm connector opens a pathway to a newer generation of balanced output devices (headphone amplifiers, digital audio players, etc.) that embrace this compact plug’s superior stability over time. A balanced headphone setup offers an even lower noise floor with great dynamic range when connected to balanced source/amp circuit outputs. The listener will thus experience a wider soundstage, tightly controlled transients and impossibly-clear instrument separation. Each cable is 9.8 feet / 3m long to accommodate unencumbered listening on gear deep within your shelves, or favourite listening chair, and a flexible adapter is included to reduce the 6.3mm to 3.5mm.

• Hi-fidelity sound
• Open-back design
• 42mm transducers
• Luxurious comfort
• Detachable cable

Specifications

• Article number (SKU)
• 508826
• Frequency response (speaker)
• 9 Hz - 41,500 Hz
• Sound pressure level (SPL)
• 104 dB (1 V)
• Impedance
• 150 Ω
• Total harmonic distortion (THD)
• < 0.04% (1 kHz, 100dB)
• Cable length
• 3 m
• Adapter
• stereo jack plug, gold-plated 1/4" (6.35 mm), unbalanced, 3-pin 4.4 mm, balanced, 5-pin
• Transducer principle
• dynamic, open
• Weight
• 260 g
• Connector
• stereo jack plug, gold-plated 1/4" (6.35 mm), unbalanced, 3-pin 4.4 mm, balanced, 5-pin
• Ear coupling
• circumaural
• Magnetic field
• 2.5 mT