Forget wireless — Sennheiser’s new HD 660S2 open-back headphones boost audiophile sound

Sennheiser HD 660S2 on white table top with grey background
(Image credit: Sennhesiser)

Sennheiser has revealed that it has updated its popular HD 660 'home listening' headphones with an S2 refresh. They officially go on sale later this month priced at $599 / £499/ AU$949, but can be pre-ordered from today (February 8). 

The best wireless headphones may be the most popular form of connectivity for the majority of wearers right now, but Sennheiser knows a thing or two about the audio benefits of wired sound and joins a growing trend for old-school cabled designs like several of the models in our best audiophile headphones. The upgraded HD 660S2 follows the entry-level IE 200 wired earbuds announced last month, and further demonstrates the company's commitment to wired audio products for audiophiles. 

The original HD 660 open-back, wired headphones have been firm audiophile favorites since they launched almost five years ago. A Sennheiser spokesperson says that the upgraded HD 660S2 addresses customer feedback with improvements to low frequency performance that sees the frequency response range extended from 8Hz to a bat-bothering 41.5kHz. Sensitivity is also revised to 300-ohm, offering better handling capabilities suited to audiophiles using dedicated home headphone amplifiers.

Aside from the bronze flourishes that appear to replace the silver branding details on the original, the new HD 660S2 look very similar indeed. Sennheiser tells us that additional design tweaks run to a modified earcups that is said to lower the resonant frequency of the casing, while the open-back mesh grilles offer improved airflow to aid driver movement and performance.

Sennheiser HD 660 S2 lifestyle shot

(Image credit: Sennheiser)

Sennheiser HD 660S2: Price and availability

Sennheiser's Audiophile Product Manager, Jermo Koehnke, says of the new Sennheiser HD 660S2 "With precision and power like no other and new sensitivity across all frequencies, listeners will hear details they’ve never heard before, especially at the lower end of the spectrum.” 

With the same folding hinges, plush ear cushions and on-head weight of 260g (around 9 ounces), the new HD 660S2 should provide the same high comfort levels for long listening sessions as its predecessor.

Available in a jet-black finish and supplied with a storage pouch, the HD 660S2 ships with two 1.8m (5.8 feet) user-detachable cables that terminate to 6.3mm (1/4-inch) single-ended stereo and 4.4mm balanced stereo jack plugs, respectively. A 6.3mm to 3.5mm (1/8-inch) adapter is also included, for use with popular hi-fi gear from DAC/amps, DAPs, and dedicated amplifiers such as the Sennheiser HDV 820. 

Once again, the Sennheiser HD 660S2 will cost $599 / £499/ AU$949 when they go on sale on February 21. In the meantime, they can be pre-ordered via the Sennheiser website.

Lee Dunkley
Audio Editor

As a former editor of the U.K.'s Hi-Fi Choice magazine, Lee is passionate about all kinds of audio tech and has been providing sound advice to enable consumers to make informed buying decisions since he joined Which? magazine as a product tester in the 1990s. Lee covers all things audio for Tom's Guide, including headphones, wireless speakers and soundbars and loves to connect and share the mindfulness benefits that listening to music in the very best quality can bring.