Sennheiser HD 620S Closed-Back Over-Ear Headphones

Closed-back audiophile headphones

The Sennheiser HD 620S is a pair of closed-back over-ear headphones built for listeners who want isolation without losing an open, speaker-like presentation. Angled 42 mm transducers with 38 mm diaphragms and a 150 ohm aluminum voice coil create a wide soundstage while keeping sound inside the ear cups. The design suits focused music sessions, immersive gaming and long desk work where distraction-free audio matters.

Thermals noise and power draw

Passive acoustic isolation handles external noise instead of active cancellation, so there is no battery, no fan and no electrical noise floor to manage. The 150 ohm impedance and 110 dB sensitivity at 1 V RMS mean the headphones draw very little power from a standard 3.5 mm source while keeping distortion below 0.05 percent at 90 dB SPL. Comfort-focused venting and artificial leather pads reduce heat build-up during extended wear.

150 ohm impedance decides fit

At 150 ohms the HD 620S needs a source that can deliver enough voltage for full dynamics; a low-voltage phone jack may sound quiet or thin. Buyers whose only output is a weak portable jack should note this constraint. The package includes a 1.8 m detachable cable and a 3.5 mm to 6.3 mm adapter for wider device compatibility.