Sennheiser HD 660S 2 suddenly look like the ultimate open-back headphones

The second-gen HD 660S headphones bring more audio precision, especially for low-end frequencies, making for an ace audiophile upgrade

Sennheiser HD 660S Mk2
(Image credit: Sennheiser)

When it comes to high-end headphones Sennheiser knows more than a thing or two. Its original HD 660S open-back cans were an audiophile sensation for many listeners, acting as an ideal at-home listening experience.

Now these open-back audiophile headphones have the ultimate upgrade: a second-generation model! Named the Sennheiser HD 660S2, these updated cans promise to deliver even more for audio fans. An early 2023 contender for the best wired headphones already, perhaps? 

So what exactly is new in the HD 660S Mk2? A quick glance at the specification reveals a small but critical detail: the frequency response is wider than before, covering 8Hz through to 41,500Hz. That's an even lower-end capability than the original model.

Sennheiser explains this in a much more eloquent way though, claiming that the "Sennheiser HD 660S2 offers listeners what they requested most from the headphones’ predecessor. 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."

Sennheiser HD 660S2 being worn

(Image credit: Sennheiser)

This more dynamic listen uses "enhanced sub-bass tuning" thanks to improved transducer airflow and a refined voice coil as part of the design. But, crucially, this more capable low-end output doesn't overbear any of the other all-important frequencies, delivering a supposedly warmer overall sound profile.

And how much will you need to pay for the pleasure of buying a pair of Sennheiser HD 660S2 open-back headphones? The pre-order page is open now, with £499 being the price in the UK, $599.95 being what you'll pay in the USA. They'll be on sale from 21 February.

Considering just how much some open-back headphones cost, that's not entirely unreasonable – although the previous model can be found for even less if you shop around. You'll probably want to budget for one of the best headphones DACs to pair with your new headphones too, if you don't already have the necessary gear. 

Mike Lowe
Tech Editor

Mike is the Tech Editor at He's been writing about consumer technology for 15 years and, as a phones expert, has seen hundreds of handsets over the years – swathes of Android devices, a smattering of iPhones, and a batch of Windows Phone too (remember those?). But that's not all, as a tech and audio aficionado his beat at T3 also covers tablets, laptops, gaming, home cinema, TVs, speakers and more – there's barely a tech stone unturned he's not had a hand on. Previously the Reviews Editor at Pocket-lint for 10 years, he's also provided work for publications such as Wired, The Guardian, Metro, and more. In addition to his tech knowledge, Mike is also a flights and travel expert, having travelled the globe extensively. You'll likely find him setting up a new mobile phone, critiquing the next MacBook, all while planning his next getaway... or cycling somewhere.