Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Audio-Technica - ATH-R70xa | Sennheiser - HD 660S2 |
|---|---|---|
| Weight | 210 g | 260 g |
| Driver size | 45 mm | 42 mm |
Between the ATH-R70xa and HD 660S2, the ATH-R70xa comes out ahead in weight / driver size, while the HD 660S2 wins on several specs. Overall, the ATH-R70xa scores 54.7 and the HD 660S2 scores 52.5 on our Mars Score.
Which should you buy?
These two are nearly even on the Mars Score (54.7 vs 52.5). The decision is not about overall quality — both clear the bar — it is about which specific trade-offs fit your use.
Pick the ATH-R70xa if you carry the device everywhere and weight or thickness has been the deciding factor before. The biggest gaps in its favor are weight, driver size. The single most decisive one: Weight — 50.00 g less. 210 vs 260.
The HD 660S2 similarly does not carry a headline advantage on the popular specs — look at the full table for category-specific deltas.
Both ship with comparable battery life, active noise cancellation, spatial audio, so those specs do not separate the two — focus on the differences below.
Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity says both are well-rounded; the differences are about trade-offs, not quality.
Which should you buy: Audio-Technica - ATH-R70xa or Sennheiser - HD 660S2?
Audio-Technica - ATH-R70xa leads the current Mars Score by 2.2 points.The more useful decision is the trade-off behind that result: compare driver size, weight against the way you will actually use the product.
Choose Audio-Technica - ATH-R70xa if…
Audio-Technica - ATH-R70xa has the measurable edge on weight g, driver size mm.
Choose Sennheiser - HD 660S2 if…
Sennheiser - HD 660S2 does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
Why Audio-Technica - ATH-R70xa wins
- ▲Weight — 50.00 g less. 210 vs 260.
- ▲Driver size — 7.14% more. 45 mm vs 42 mm.
Why Sennheiser - HD 660S2 wins
- No decisive advantages.
Spec comparison
Design
| Spec | Audio-Technica - ATH-R70xa | Sennheiser - HD 660S2 |
|---|---|---|
| Type | over-ear | over-ear |
| Weight | 210 glead | 260 g |
| Water resistance | none | none |
Audio
| Spec | Audio-Technica - ATH-R70xa | Sennheiser - HD 660S2 |
|---|---|---|
| Driver sizeⓘ | 45 mmlead | 42 mm |
| Impedanceⓘ | 470 Ωlead | 300 Ω |
| Sensitivityⓘ | 99 dB | 104 dBlead |
| Active noise cancellationⓘ | false | false |
| Transparency mode | false | false |
| Spatial audioⓘ | false | false |
Battery
| Spec | Audio-Technica - ATH-R70xa | Sennheiser - HD 660S2 |
|---|---|---|
| Battery lifeⓘ | 0 h | 0 h |
| Fast chargeⓘ | false | false |
Connectivity
| Spec | Audio-Technica - ATH-R70xa | Sennheiser - HD 660S2 |
|---|---|---|
| Bluetoothⓘ | 0 | 0 |
| Multipointⓘ | false | false |
| 3.5mm jack | true | true |
| LDACⓘ | false | false |
| aptX HDⓘ | false | false |
Frequently asked
Which has better battery life, ATH-R70xa or HD 660S2?+
HD 660S2 lasts 0 hours vs 0 hours.
Do ATH-R70xa or HD 660S2 have active noise cancellation?+
Neither model has active noise cancellation.
Which supports LDAC, ATH-R70xa or HD 660S2?+
Neither supports LDAC.