Sennheiser’s Iconic HD 600 Series Headphones Gets A Major Upgrade

Sennheiser’s Iconic HD 600 Series Headphones Gets A Major Upgrade

Today one of the world’s best-loved headphone brands announced that its iconic HD 600 Series has been updated. It’s fair to say the Sennheiser 600 Series has been loved by music and audio enthusiasts looking for high-end headphone performance. The new HD 660 S2 results from feedback from the company’s loyal customer base asking for a pair of open-back headphones that offer reference-level detail with an impactful bass.

In a press release to mark the launch of the new model, Sennheiser says the upgrade offers a “more dramatic listen with greater intensity from enhanced sub-bass tuning, extracting dynamic impact and emotion from audio enthusiasts’ favorite recordings. The updated acoustics offer a delightful new way to experience music all over again.”

It’s always a bit of a gamble when reimagining a product so well-loved by a loyal band of customers. Sennheiser says that the HD 660S2 ​improves the well-love classic by ensuring that its best traits are retained. This upgrade was challenging, starting with the lowest end of the frequency plot. The HD 660S2s have been given a warmer bass that complements the original headphones’ smooth treble response that works so well with vocals while enabling the timbre and unique character of individual instruments to shine through.

The press release says that the entire frequency spectrum delivered by the HD 660S2 creates a refined listening experience thanks to improved transducer airflow and a refined voice coil. The upshot is a better depth and nuance of low-frequency passages, adding “dramatic flair” to any music. Listeners should notice a more profound, clearer bass without impacting the expansive detail the classic series is known for.

By reducing the voice coil’s weight, Sennheiser’s engineers say the impulse response has been improved, bringing hyper-realistic textures to the forefront of performances. The overall experience is “smoother and warmer” than the original HD 660S. The overall impedance matches the HD 600 and HD 650 with an audiophile-friendly 300Ω, producing punchy dynamics and impressively low distortion.


The new headphones were designed in Germany and are manufactured at Sennheiser’s state-of-the-art factory in Ireland. The HD 660S2 offers the same build quality and materials as the original design. Plush earpads and a comfy headband with plenty of padding position the earcups at an optimal distance from the ear, producing a spacious soundstage with plenty of detail.

The transducer surround drops the resonant frequency from the 110Hz of the original HD 660S down to 70Hz giving more emphasis to dynamic sounds like kick drums. The outer mesh grilles of each earcup are designed to allow airflow at the ideal impedance for open-back listening sessions.

The HD 660S2 ships with two 1.8-meter (5.8 ft) user-detachable cables that terminate to 6.3mm (1/4-inch) single-ended stereo and 4.4mm balanced stereo jack plugs, respectively. A 6.3 mm to 3.5 mm (1/8-inch) adapter for use with popular sources DAC-amps, DAPs and dedicated amplifiers like Sennheiser’s HDV 820. Classy bronze accents on the mesh earcups are contrasted against a jet-black finish.

Pricing & Availability: ​The Sennheiser HD 660S2 will be available for pre-order globally from 8th February 2023 and will go on sale on 21st February 2023 for $599.95 / £499 / €599.

More info:

Tech Specs:

  • Transducer principle: Dynamic, open.
  • Transducer size: 38mm.
  • Frequency response: 8Hz – 41,500Hz.
  • Impedance: 300Ω.
  • Sound pressure level (SPL): 104 dB (1 V).
  • Total harmonic distortion (THD): < 0.04% (1 kHz, 100dB).
  • Style: Over-ear.
  • Weight: 260g.
  • Adapter: 6.3mm (1⁄4-inch) to 3.5mm.
  • Connector: 6.3mm (1⁄4-inch) jack plug, 4.4mm balanced plug.
  • Cable length: 1.8m.

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