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1 / 7From the same stable as the classic HD 600, what does that extra 60S get you?
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Wired-3.5mm is the most common — on 47% of the 252 over-ear headphones we've cataloged (of 242).
below average for over-ear headphones — based on 200 of 242 we've cataloged.
Objective measurements from the SoundGuys test lab — overlay other models to see how this one compares.
Sennheiser HD 660S Frequency Response (measured on a B&K 5128)
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Measured frequency response (dB relative) against the SoundGuys Headphone Preference Curve. When the measurement goes above the dashed line, that frequency is louder than our preference curve, and when it goes below: it's quieter. Use the curve for comparison purposes only, as your taste may vary.
| Frequency (Hz) | Response (dB) |
|---|---|
| 20 | -8.5 |
| 25 | -6.4 |
| 32 | -4.7 |
| 40 | -3.2 |
| 50 | -2.3 |
| 63 | -1.8 |
| 80 | -1.5 |
| 100 | -0.7 |
| 125 | -0.4 |
| 160 | -0.5 |
| 200 | -0.6 |
| 250 | -0.5 |
| 315 | -0.7 |
| 400 | -0.8 |
| 500 | -0.8 |
| 630 | -0.5 |
| 800 | 0.0 |
| 1000 | 0.5 |
| 1250 | 1.6 |
| 1600 | 2.3 |
| 2000 | 3.0 |
| 2500 | 5.0 |
| 3150 | 7.2 |
| 4000 | 4.8 |
| 5000 | 3.2 |
| 6300 | 6.9 |
| 8000 | 6.7 |
| 10000 | 3.9 |
| 12500 | -0.3 |
| 16000 | -4.7 |
| 20000 | -18.9 |
Sennheiser HD 660S Attenuation (measured on a B&K 5128)
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Solid lines: passive isolation (dB) with ANC off — how much ambient noise the fit blocks on its own. Higher on the chart means more attenuation.
| Frequency (Hz) | Attenuation (dB) |
|---|---|
| 21 | 0.4 |
| 26 | 0.3 |
| 33 | 0.1 |
| 41 | -0.1 |
| 52 | -0.0 |
| 65 | -0.1 |
| 82 | -0.2 |
| 103 | 0.1 |
| 130 | 0.0 |
| 163 | 0.1 |
| 205 | -0.1 |
| 259 | -0.0 |
| 325 | -0.1 |
| 410 | -0.3 |
| 516 | -0.1 |
| 613 | -0.2 |
| 772 | -0.7 |
| 972 | -1.2 |
| 1220 | -1.2 |
| 1540 | 0.1 |
| 1940 | 3.3 |
| 2440 | 8.6 |
| 3070 | 7.2 |
| 3870 | 8.7 |
| 4870 | 11.5 |
| 6130 | 17.8 |
| 7720 | 16.7 |
| 9720 | 15.3 |
| 12200 | 2.3 |
| 15400 | 10.4 |
| 19400 | 11.1 |
The verdict
While it doesn't quite have the analytical sound signature of the highly regarded "reference" HD 600, it's close, and the Sennheiser HD 660S is well constructed, very comfortable, and gives a pleasant listen for hours at a time.
✓Liked: Sound quality, Comfort, Replaceable cables, Connections provided for standard and balanced amps
✕Could be better: Not a significant step up from less expensive Sennheiser models
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Own the Sennheiser HD 660S?
Three answers, four quick reads, one sentence nobody tells you before buying. Shown under a pseudonym. Sign-in needed to publish.
What readers ask about the Sennheiser HD 660S, answered by the people who own it.
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Ask the first question →Commentary and deep dives from the SoundGuys editorial team.
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Adam BirneyManaging Editor3 headphones I would buy instead of the AirPods Max 2These premium headphones deliver class-leading ANC, longer battery life, and more flexibility for less money.Dave CarrVideo Producer/WriterThe end of budget audio's best bargain: RIP HD 6XXIt was one hell of a run.
Christian ThomasEditor-at-largeWired vs wireless headphones: Which should you buy?Wired headphones do not automatically sound better.
Tom TriggsContributorThe 5 best headphones to look forward to in 2026Strap in — we're in for a wild year.Tom TriggsContributorI've reviewed headphones for over a decade: Here are 5 things I wish they did differentlyHeadphone companies: help me help youChristian ThomasEditor-at-large5 ways headphones are going to change in 2027Here's where things are headed.Christian ThomasEditor-at-large
3 of 5 would buy again
5 owners · owners report ~40 h per charge vs 40 h claimed
Comfort beat their expectations
Expected more from the fit and build
The battery beat their expectations
1 of 1 would buy again
1 owner
Nothing surprising about comfort
0 of 1 would buy again
1 owner
The noise cancelling beat their expectations
0 of 1 would buy again
1 owner · 1 photo-verified
Expected more from comfort
0 of 1 would buy again
1 owner
Comfort beat their expectations
0 of 2 would buy again
2 owners · 2 photo-verified
The noise cancelling beat their expectations
The battery beat their expectations
