Sennheiser - HD 660S2 vs Sony - WH-1000XM5

The HD 660S2 edges ahead on the Mars Score (64.2 vs 60.5), but the 3.7-point gap is small enough that the right pick comes down to which spec advantages matter to you.

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

Pick the WH-1000XM5 if you carry the device everywhere and weight or thickness has been the deciding factor before. Its strongest claims are weight, active noise cancellation, spatial audio, among others.

Both ship with comparable water resistance, 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.