When it comes to high-quality audio, SENNHEISER has long been a name synonymous with excellence. The SENNHEISER HD 660S2, their latest offering, is no exception. These headphones are a testament to the brand’s commitment to delivering top-notch audio experiences. In this review, we’ll delve into the build quality, sound quality, and overall performance of the SENNHEISER HD 660S2, so you can decide if they’re the right pair of headphones for you.
SENNHEISER HD 660S2 Build Quality
Right out of the box, the SENNHEISER HD 660S2 exude a sense of elegance. The combination of matte black and silver accents gives these headphones a sophisticated, premium look. But it’s not just about appearances; these headphones are built to last.
The materials used in the construction feel robust and durable. The ear cups and headband are adorned with plush velour padding, providing a comfortable fit even during extended listening sessions. The adjustable headband allows for a customized fit on any head size, and the headphones weigh in at a mere 260 grams, making them surprisingly lightweight for over-ear headphones.

One of the standout features of the SENNHEISER HD 660S2’s build quality is its detachable cable. The 1.8-meter cable is of high quality, and its detachability is a practical touch. This means that if the cable ever gets damaged, you can easily replace it without having to replace the entire set of headphones. Furthermore, the package includes two different connectors: a 6.3 mm (1⁄4 inch) jack plug and a 4.4 mm balanced plug, offering versatility in how you choose to connect to your audio source.
Overall, the build quality of the SENNHEISER HD 660S2 is top-notch. These headphones feel like they can withstand the test of time and the rigors of daily use.
SENNHEISER HD 660S2 Sound Quality
Now, let’s talk about what really matters with headphones: the sound quality. The SENNHEISER HD 660S2 doesn’t disappoint. With a 38 mm dynamic, open transducer principle, they are designed to deliver an exceptional audio experience.
The frequency response of 8 – 41,500 Hz means that these headphones cover an impressively wide range of frequencies. Whether you’re listening to thunderous basslines or the delicate nuances of a classical piece, the SENNHEISER HD 660S2 handles it all with grace. The soundstage they offer is expansive, allowing you to immerse yourself in your favorite music like never before.
One of the unique features of these headphones is their high impedance of 300 Ω. While this might make them less suitable for on-the-go listening without an amplifier, it’s a boon for audiophiles who crave precision and detail in their music. The SENNHEISER HD 660S2 truly shine when paired with a quality amplifier, allowing you to unlock their full potential.
The sound pressure level (SPL) of 104 dB at 1 kHz and 1 Vrms ensures that even at lower volumes, you won’t miss out on any subtleties in your music. And when you crank up the volume, these headphones maintain their composure, with a total harmonic distortion (THD) of less than 0.04% at 1 kHz and 100 dB.

Whether you’re into rock, jazz, classical, or electronic music, the SENNHEISER HD 660S2 offers a balanced and natural sound signature. The bass is tight and controlled, the mids are lush and detailed, and the highs are crisp without being piercing. These headphones excel in reproducing vocals, making every lyric and note feel like a private concert.
SENNHEISER HD 660S2 – Performance
In terms of performance, the SENNHEISER HD 660S2 is designed to elevate your audio experience to new heights. The open-back design, combined with their impressive transducer and frequency response, creates a sense of space and depth that few headphones can match. This makes them ideal for critical listening and audiophile-grade setups.
The headphones’ ear coupling is over-ear, which enhances comfort and noise isolation. However, it’s important to note that these headphones are open-back, so they do allow some sound leakage. They may not be the best choice for use in a noisy office environment, but they excel in quieter settings where you can fully appreciate their soundstage.
The included adapter, which converts the 6.3 mm (1⁄4 inch) plug to 3.5 mm, adds to the versatility of the SENNHEISER HD 660S2. You can easily connect them to a wide range of devices, from high-end audio equipment to your smartphone or laptop. And if you’re a fan of balanced audio, the 4.4 mm balanced plug option is a welcome addition.

In Conclusion…
The SENNHEISER HD 660S2 is a masterpiece in the world of headphones. Their build quality, with attention to comfort and durability, ensures they’re more than just a pretty face. When it comes to sound quality, these headphones deliver a sonic experience that will leave you spellbound. The wide frequency response, high impedance, and low THD make them a favorite among audiophiles seeking accuracy and detail.
While they may not be the most portable option due to their open-back design and high impedance, the SENNHEISER HD 660S2 shines in quiet listening environments where you can fully appreciate their sonic prowess. Whether you’re a music enthusiast, a gamer, or a professional audio engineer, these headphones are a worthy addition to your setup.
In the world of audio, the SENNHEISER HD 660S2 stands as a testament to the brand’s commitment to excellence. If you’re in search of headphones that deliver a symphony for the senses, these are a harmonious choice that will elevate your listening experience to new heights. SENNHEISER HD 660S2 price: $499.95