Packaging and Accessories
My main issue with the Sennheiser HD660S2 starts from its packaging which fails to match its high value because the product comes in a weak cardboard box that lacks any protective foam material despite its price of nearly 17 million VND. The company demonstrates high confidence about product durability because it uses careless packaging methods. The DT1990 Pro and Anada and HD660S predecessor products all provide better packaging than the current product. The headphone accessories are also quite meager, consisting of two cables using the HD6XX series’ proprietary connector, along with an adapter to convert from a 6.3mm jack to a 3.5mm jack.
Design
I immediately thought about the work situation for Sennheiser designers at that moment when I first picked up the Sennheiser HD660S2. The HD660S2 has an identical design to its predecessor, the HD660S. The HD660S2 displays a bronze-brown logo while the HD660S shows a silver logo that uses white lettering. The HD660S2 maintains complete design continuity with its predecessor which enables it to endure damage because users can treat it with less caution than Focal and Hifiman headphones require. A plastic material constitutes most of the product which results in an extremely low weight. The HD660S2 headband clamp shows strong initial pressure which makes extended usage uncomfortable for users because this issue exists in all HD6XX series headphones. You can use books or similar materials to keep the headphones stable because the headband clamp will start to loosen after 1-2 weeks of usage.
Specifications and Sound Quality
The Sennheiser HD660S2 requires 300Ω impedance and 104dB sensitivity for its operation. The device requires strong power to operate but it remains workable. A mid-range portable DAC/Amp which includes the iFi IDSD Signature serves as a basic requirement for users who need to drive their system with either a DAC or an amplifier solution. The sound quality assessment of Sennheiser HD660S2 requires IDSD Diablo as a testing device which provides sufficient power to drive the headphones at their maximum performance level.
The HD660S2 maintains the original sound signature of the HD660S model, which now features enhanced sub-bass to improve bass performance. The HD660S2 produces bass sounds which deliver strong force without any distortion that continues after the sound ends. The midrange maintains its thick warm sound which resembles Ananda and DT1990 Pro yet shows reduced mid-range details. The HD660S2 produces smooth treble which loses its brightness after a short time, which will disappoint listeners who want clear high-pitched sounds. The Sennheiser HD660S2 soundstage provides enough width to create a warm intimate space which listeners can use to enjoy Jazz and Acoustic music.
In summary
The Sennheiser HD660S2 demonstrates better sound performance than the HD660S2 which features a different sound signature. The headphone’s high price and limited accessories will prevent most customers from buying this product which they planned to purchase. The decision to buy this product remains personal for each individual yet I believe this headphone offers worth experiencing because it delivers essential qualities of extended product life and pleasant sound and versatile use and a brand name that audiophiles trust.
Sennheiser HD 660S2 – Audiophile Open-Back Over Ear Headphones with Deep Bass Extension and Refined Acoustic Performance, Over-Ear Headphones for PC, Music, Gaming, Podcasts, Premium Black:
Tech Reviewer & Product Analyst
Định Bia has spent over 10 years testing consumer electronics with a focus on smart technology. He work as a product advisor at Biareview where he helped customers find the right devices for their needs. He personally tests every product featured on this site using a consistent evaluation framework covering quality, durability, and value. All reviews are based on experience, not influenced by the manufacturer.