Sennheiser HD 650

The HD 650 is an open-back, over-ear reference headphone with a 300-ohm impedance and a frequency response of 10 Hz to 41 kHz. The 42mm transducer uses an aluminium voice coil diaphragm tuned for critical listening, with a slightly warm low-midrange character that sits between the leaner HD 600 and the more coloured HD 660 S. That signature makes it forgiving on long sessions without sacrificing the transient detail needed for mix decisions.

The aluminium voice coils and neodymium magnets are hand-selected and channel-matched at the factory. The cable is detachable and impedance-matched, terminating in a 6.35mm jack with a 3.5mm adapter included. At 300 ohms the HD 650 genuinely benefits from a headphone amplifier: feeding it from a laptop headphone output will leave noticeable dynamic range on the table.