The frequency response differs (8 Hz -41500 Hz vs 5 Hz -40000 Hz), which can influence how well the headphones reproduce lows, mids, and highs. There is a noticeable difference in weight (260 Gm vs 385 Gm), which may affect comfort during extended use. Both headphones offer solid battery performance, making them suitable for long listening sessions and travel. The driver size differs between the two (38 mm vs 50 mm), which can influence sound depth, bass response, and overall audio clarity. Sennheiser HD 660S2 and Denon AH-D5200 offer different noise cancellation capabilities (AMBIENT vs NA), which can impact how effectively they block external noise. If you're comparing Sennheiser HD 660S2 and Denon AH-D5200, both models offer a strong combination of sound performance, comfort, and modern wireless features. Both models support modern Bluetooth connectivity, ensuring stable wireless performance with compatible devices. Impedance levels vary (300 ohm vs 24 ohm), which can affect compatibility and audio output when used with different devices. From a usability standpoint, both models provide a reliable and premium headphone experience.

Verdict: Choosing between Sennheiser HD 660S2 and Denon AH-D5200 depends on whether you value better sound, longer battery life, or enhanced features.