Sennheiser - HD 660S2 vs Sennheiser - HD 660S2

These two are nearly even on the Mars Score (64.2 vs 61.4). The decision isn't about overall quality — both clear the bar — it's about which specific trade-offs fit your use.

Pick the HD 660S2 if you care most about driver size. The biggest gaps in its favor are driver size.

The HD 660S2 similarly doesn't 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 don't 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 tells you both are well-rounded; the differences are about trade-offs, not quality.