
Sennheiser HD 660S2
Score: 79/100
Audio-Technica ATH-R50X
Score: 76/100Rankings

The Sennheiser HD 660S2 is an open-back, wired audiophile headphone delivering refined detail, deep bass extension, and a premium build. Its high impedance and lack of wireless or ANC limit use to desktop setups with a quality amp. Best suited for critical listeners and home-studio environments.

The ATH-R50x offers a lightweight open-back design with strong bass and comfortable wear, making it suitable for critical listening in quiet environments. However, its pronounced treble peak and lack of isolation limit its use in noisy settings. Best for studio professionals and audiophiles who prioritize soundstage over isolation.
| Attribute | ![]() | ![]() |
|---|---|---|
38 mm | 45 mmbest | |
| ↓ lower better | 300 g | 207 gbest |
300 Ωbest | 50 Ω | |
104 dB SPLbest | 93.3 dB SPL |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Audio(4) | ||
Frequency Response | 8-41500 Hz | 5-40000 |
Driver Size (mm) | 38 mm | 45 mm |
Impedance (Ω) | 300 Ω | 50 Ω |
Sensitivity (dB SPL) | 104 dB SPL | 93.3 dB SPL |
Build & Design(2) | ||
Weight (g) | 300 g | 207 g |
Dimensions (H×W×D) (mm) | 177.8x177.8x76.2 mm | 199.9x169.9x101.6 mm |

Products in the top-left offer the best value (high score, low price).

Professional reviewers consider the HD 660S2 a significant technical upgrade over the original HD 660S, citing its refined voice coil, lower resonant frequency, and enhanced airflow as key contributors to superior bass extension, clarity, and overall resolution.
Everyday users praise the HD 660S2 for its detailed, balanced sound and comfortable velour pads, while noting the need for a solid amplifier and the open-back design's lack of isolation.

“good clarity from the 4 kHz peak but criticizes the 6-10 kHz 10 dB peak for sharpness”

“lightweight comfort during long wear”




Professional reviewers commend the ATH-R50x for its lightweight comfort, strong bass for an open-back design, accurate midrange, and easy driveability at 50 Ω, noting its natural soundstage and precise transients make it a solid reference tool. However, they point out a pronounced treble peak between 6 kHz and 10 kHz that can sound harsh, and the inherent sound leakage of the open-back architecture limits its use in noisy settings.
Everyday users echo the professional praise for comfort and spacious sound, especially appreciating the bass punch and value for studio use. Recurring criticisms focus on the sharp treble in the upper mids/highs and the lack of isolation, which can cause fatigue and disturb others in shared spaces.