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Black over-ear headphones with open-back ear cups and headband

Sennheiser

Sennheiser HD 660S2 Wired Audiophile Stereo Headphone

SKU CH-C838-EZPCR

Open-back audiophile headphones with 300-ohm impedance and 42mm transducers deliver natural high-fidelity sound down to 8 Hz

  • ColorBlack
  • Natural, relaxed high-fidelity sound with extra sub-bass thanks to 300-ohm impedance
  • Airflow-optimised 42 mm transducers with vented magnet system minimise distortion
  • Deep bass pressure lets you feel 27.5 Hz piano notes and 45-60 Hz kick drums
  • Open-back design and plush ear cushions provide breathability for long listening sessions
  • Wide 8 Hz to 41,500 Hz frequency response with detachable cables for desktop use

Wired Audiophile Headphone

The Sennheiser HD 660S2 is a wired open-back headphone built for critical listening. It uses 42mm transducers with a vented magnet system and 300 Ohm impedance to deliver a frequency response of 8 Hz to 41,500 Hz. Detachable cables terminate in a 3.5mm jack for desktop connections.

For dedicated listeners not for commuters

This model suits audiophiles who want natural timbre and deep sub-bass extension down to 27.5 Hz for studio or home use. The open-back design leaks sound and blocks no outside noise so it is not for noisy environments portable use or anyone needing a built-in microphone for calls.

300 Ohm impedance decides the source

The 300 Ohm rating means the headphones need a dedicated headphone amplifier or high-output interface to reach proper volume and control. A standard phone or laptop jack will likely sound too quiet and lack dynamics so check your source gear before buying.

Highlights

  • Natural, relaxed high-fidelity sound with extra sub-bass thanks to 300-ohm impedance
  • Airflow-optimised 42 mm transducers with vented magnet system minimise distortion
  • Deep bass pressure lets you feel 27.5 Hz piano notes and 45-60 Hz kick drums
  • Open-back design and plush ear cushions provide breathability for long listening sessions
  • Wide 8 Hz to 41,500 Hz frequency response with detachable cables for desktop use

Specifications

ColorBlack

Questions about this item

What source output do I need to drive the 300 Ohm impedance?

A headphone amplifier or audio interface with a 3.5 mm jack that can supply enough voltage for 300 Ohm loads.

Will the open-back design leak sound into my existing desktop microphone?

Yes, the open-back cups radiate sound outward so a nearby mic will pick up playback; use a directional mic or increase distance.

How can I verify the 8 Hz – 41,500 Hz response is performing correctly?

Play a 27.5 Hz piano note and a 45–60 Hz kick drum; both should be audible and felt without distortion.

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