Breathtaking midrange ; Relaxed, undemanding listen ; Smooth presentation

Soft bass ; Can be bettered for dynamics and detail

The Sennheisers have a charming smoothness to their sound, but their soft bass and lack of dynamic thrust hold them back.

Properly made, comfortable and durable ; Burly, spacious and informative sound ; Balanced or unbalanced connections

Treble sounds are slightly inhibited ; Not fans of inferior sources ; Awkward 6.3mm-3.5mm adapter

There’s ‘unfashionable’ and then there’s wired headphones. But where outright performance in nearly every meaningful audio department is concerned, the Sennheiser HD 660S2 have plenty to recommend them - as long as your source of music is up to the...

Fantastic low end ; If they fit you, you’ll find they are extremely comfortable ; Exceptional overall sound presentation

Folks with large heads might find their fit is too tight ; Soft-sided carry bag offers too little protection ; Pricey

Sennheiser has released a headphone that’s sure to generate controversy in the audiophile community, but the company has delivered a truly engaging listening experience for everyone not obsessed with specs and benchmarks.

Improved sub-bass performance ; Excellent choice for OTL amplifier owners ; Modern cable terminations

Upper-mids at times needs a bit of EQ for presence ; High lateral clamping pressure when brand new

The Sennheiser HD 660S2 is a clear technical step up on the HD 660S. It offers superior extension on both ends of the spectrum, stretching the presentation taller and deeper and injecting some improved weight and dynamics over the original tuning. The...

Beautiful tonal balance with great detail, and more transparent soundstage than its predecessor. Tighter and better defined bass reproduction.

Some people may find the fit tight.

The Sennheiser HD660S2 are a very successful update to one of our favourite headphones. They deliver a more open and transparent soundstage than its predecessor without radically changing the sound signature. You still get a comfortable and balanced...