The driver size differs between the two (NA vs 40 mm), which can influence sound depth, bass response, and overall audio clarity. The frequency response differs (20 Hz-20,000 Hz vs 7Hz - 37,000Hz), which can influence how well the headphones reproduce lows, mids, and highs. There is a noticeable difference in weight (380 g vs 250 g), which may affect comfort during extended use. Impedance levels vary (32 Ohms vs 36 Ohms), which can affect compatibility and audio output when used with different devices. If you're comparing Sennheiser HD-451 and Denon AH-D340, both models offer a strong combination of sound performance, comfort, and modern wireless features. From a usability standpoint, both models provide a reliable and premium headphone experience. Sennheiser HD-451 and Denon AH-D340 offer different noise cancellation capabilities (Yes vs NA), which can impact how effectively they block external noise. Both headphones offer solid battery performance, making them suitable for long listening sessions and travel. Both models support modern Bluetooth connectivity, ensuring stable wireless performance with compatible devices.

Verdict: Both models are competitive, and your decision should be based on your usage needs and preferred features.