There is a noticeable difference in weight (NA vs 131 g), which may affect comfort during extended use. Impedance levels vary (60 Ohms vs 32 ohm), which can affect compatibility and audio output when used with different devices. In general, both options are suitable for everyday use including music, calls, travel, and work-from-home scenarios. Both headphones are equipped with capable drivers that deliver balanced sound output suitable for music, calls, and entertainment. Koss QZ99 and Beyerdynamic DTX 350M are premium wireless headphones designed to deliver high-quality sound along with advanced features like noise cancellation and long battery life. Both models support modern Bluetooth connectivity, ensuring stable wireless performance with compatible devices. The frequency response differs (40 Hz - 20000 Hz vs 22 - 18,000 Hz), which can influence how well the headphones reproduce lows, mids, and highs. Both headphones offer solid battery performance, making them suitable for long listening sessions and travel. Koss QZ99 and Beyerdynamic DTX 350M offer different noise cancellation capabilities (Yes vs NA), which can impact how effectively they block external noise.

Verdict: Choosing between Koss QZ99 and Beyerdynamic DTX 350M depends on whether you value better sound, longer battery life, or enhanced features.