Sennheiser HD 660S2

Praised by Experts

• ✓Professional reviewers highlight the redesigned voice coil’s higher magnetic force and improved electrical dampening for a cleaner impulse response.
• ✓The more compliant surround that drops the resonant frequency to 70 Hz yields double the low‑frequency sound pressure, praised for deeper bass.
• ✓Optimized airflow around the transducer is noted for increasing sensitivity and delivering greater detail across the spectrum.
• ✓Critics commend the great timbre, deep accurate sub‑bass, and the increased precision, speed, and resolution compared to the original HD 660S.

Criticized by Experts

• ✗The notorious high clamping force remains, which reviewers say can be uncomfortable during long sessions.
• ✗Pad compression over time is observed to gradually reduce clarity and affect the 5 kHz response, similar to issues seen with the HD 650.
• ✗The 300 Ω impedance is seen as a barrier for users without a dedicated headphone amplifier, limiting portability.
• ✗Open‑back design is repeatedly mentioned as a drawback for use in noisy environments or for those needing isolation.