Display & Audio Setup
Sennheiser HD 660S2
By Nick Miles · Updated 2026-10-03 · 9 expert sources
Pros
- +Sennheiser's step up from the HD 600/650 family: a 38 mm open dynamic driver rated 8 Hz to 41.5 kHz (Sennheiser)
- +PCMag found a spacious, neutral-leaning sound that keeps its bass depth, and Digital Trends lists excellent bass response
- +What Hi-Fi? praises a breathtaking midrange and a relaxed, undemanding listen
- +Ships with a 6.3 mm cable and a 4.4 mm balanced cable, plus a 6.3-to-3.5 mm adapter (What Hi-Fi?)
- +T3 calls it properly made, comfortable and durable
Cons
- −300-ohm impedance (Sennheiser): RTINGS says it needs a powerful amp, and TechRadar says it needs a separate amp to get the most out of it
- −What Hi-Fi? found the bass soft and short on dynamic thrust, the opposite of PCMag's verdict
- −Digital Trends warns the clamping force may feel too strong
- −Open-back and non-folding: RTINGS rates it poor for office work and impractical for travel
Score breakdown
- Expert consensus7.6
- Effectiveness8.5
- Build safety9.0
- Durability9.0
- Value8.2
Build safety is provisional. Our 2026-10-03 search of CPSC recall data found no recall for this product, and no safety, heat or failure reports turned up in our sources, but we have not yet verified its UL/ETL or equivalent safety certification. The 9.0 is a placeholder until that evidence is reviewed, not a certified rating.
What the experts say
“The Sennheisers have a charming smoothness to their sound, but their soft bass and lack of dynamic thrust hold them back.”
“To justify their high-end price, the wired Sennheiser HD 660S2 headphones achieve a spacious, neutral-leaning listening experience without sacrificing bass depth.”
“In addition, their impedance has risen from 150 ohms to 300 ohms (with a sensitivity of 104 dB/SPL), so you'll need a powerful amp to drive them effectively.”